ResearchPad - bone-and-mineral-case-reports-i Default RSS Feed en-us © 2020 Newgen KnowledgeWorks <![CDATA[SAT-379 Giant Parathyroid Adenoma]]> Giant parathyroid adenoma

Background: Primary hyperparathyroidism is the most common cause of hypercalcemia. On ultrasound PTH adenomas are typically homogenous, hypoechoic, oval or bean-shaped with peripheral vascularity.

Clinical Case: A 60 year old woman with a history of calcium oxalate nephrolithiasis presented with fatigue, worsening depression, body aches of 3 months duration. Labs showed a serum calcium 11.1 mg/dl (normal range 8.5–10.1 mg/dl), PTH 114.3 pg/ml (normal range 12–88 pg/ml), 25 OH Vitamin D 11 ng/ml (normal range above 29 ng/ml), alkaline phosphatase 137IU/L (normal range 27–120 IU/L), spot urine calcium 34.8 mg/dl, spot urine creatinine 92.1 mg/dl (estimated 24 hour urine calcium 415 mg/dl). She was started on Vitamin D 1000 IU daily. A PTH scan with SPECT/CT showed a right parathyroid adenoma and possible thyroid nodules. A neck ultrasound demonstrated a left 1.5 cm thyroid nodule and a right 3cm lesion. She underwent FNA of the left thyroid nodule and pathology was suggestive of a benign follicular nodule. She underwent parathyroid gland exploration with resection of the right lesion which was a 3.5 x 2.5 x 1.4 cm right superior 5.68 gm PTH adenoma. Postoperatively her serum calcium normalized to 10.1 mg/dl, PTH was 8.4 pg/ml, 25 OH vitamin D was 15 ng/ml. Her Vitamin D dose was increased.

Clinical Lessons: A normal parathyroid gland typically weighs 30–60 mg and is 3–4 mm in size. The differential diagnosis for large parathyroid lesions is parathyroid carcinoma vs giant parathyroid adenoma. Although there is not a definitive size cutoff to define giant parathyroid adenomas, a size greater than 3.5 gm has been used (1). On ultrasound giant parathyroid adenomas are homogenous with smooth borders whereas parathyroid carcinomas are large lobulated heterogeneous hypoechoic lesions (2). A depth/width ratio on ultrasound may be the ultrasound parameter with greatest discriminatory capacity as a depth/width ratio greater than or equal to 1 had 94% sensitivity and 95% specificity for parathyroid carcinoma (2). Whether vitamin D deficiency is a risk factor for the development of large parathyroid glands is controversial as there has been conflicting data on this (1,3). Because there is no serum calcium level that distinguishes parathyroid carcinoma from a parathyroid adenoma neck ultrasound may be a helpful tool in evaluating these patients.


1. Spanhemier PM, Stoltze AJ, Howe JR, et al. Do giant PTH adenomas represent a distinct clinical entity? Surgery. 2013 Oct; 154(4):714–719.

2. Hara H, Igarashi A, Yano Y, et al. Ultrasonagraphic features of PTH carcinoma. Endocr J. 2001 April 48(2):213–217.

3. Rao DS, Honasoge M, Divine GW, et al. Effect of vitamin D nutrition on PTH adenoma weight: pathogenetic and clinical implications. J Clin Endocrinol Metab. 2000 Mar 85(3): 1054–1058.

<![CDATA[SAT-343 Diagnosis and Management of Pseudohypoparathyroidism Type 1B]]> Background: Pseudohypoparathyroidism (PHP) is a heterogeneous group of disorders characterized by end-organ resistance to PTH. Most subtypes are caused by pathogenic variants or epigenetic alterations in GNAS, which encodes the alpha subunit of the G protein regulating end-organ response to PTH. PHP type 1B (PHP1B) is caused by methylation defects in GNAS and presents with isolated renal PTH resistance. Clinical Case: A 29-year-old gentleman presented with intermittent muscle spasms, perioral and digital paresthesias, fatigue, and anxiety. Family history was notable for similar symptoms in his sister and nephew. Physical examination revealed normal stature, non-dysmorphic facies, and no soft tissue ossifications or skeletal anomalies. Chvostek sign was positive. Laboratory studies showed total calcium 6.0 mg/dL (n 8.6–10.0 mg/dL), phosphorus 6.8 mg/dL (n 2.5–3.5 mg/dL), creatinine 0.8 mg/dL (n 0.8–1.3 mg/dL), albumin 5.0 (n 3.5–5.0 mg/dL), PTH 231 pg/mL (n 15–65 pg/mL), total 25-hydroxyvitamin D 19 mg/mL (n 20–50 ng/mL), and 1,25-dihydroxyvitamin D 45 pg/mL (n 18–64 pg/mL). Additional endocrine testing showed TSH 6.4 mIU/L (n 0.3–4.2 mIU/L), free T4 1.1 ng/dL (n 0.9–1.7 ng/dL), and TPO antibody <0.3 IU/mL (n <9.0 IU/mL). Renal ultrasound was normal. CT head showed diffuse intracranial calcifications. He was diagnosed with PHP1B and started on calcitriol, cholecalciferol, and calcium carbonate. He declined genetic testing. Repeat laboratory studies were improved with total calcium 8.5 mg/dL, phosphorus 3.9 mg/dL, total 25-hydroxyvitamin D 49 mg/mL, PTH 124 pg/mL, and 24-hour urinary calcium 269 mg (n <250 mg). Conclusion: International consensus guidelines for the diagnosis and management of PHP and related disorders were recently published by Mantovani et al. in 2018. Proposed clinical and biochemical major criteria include PTH resistance, ectopic ossifications, early-onset obesity, TSH resistance, and Albright hereditary osteodystrophy (AHO; round facies, short stature, brachydactyly, developmental delay). Unlike PHP type 1A, PHP1B often presents later in life and features of AHO are usually absent, so diagnosis requires a high degree of clinical suspicion. It is recommended that patients with suspected PHP have molecular confirmation with sequencing, methylation, and/or copy number variant analysis of GNAS. Routine monitoring of calcium, phosphorus, and PTH levels and treatment with active vitamin D analogues with or without calcium supplements are advised to maintain normal calcium and phosphorus and PTH <2 times the upper limit of normal. Other recommendations include renal imaging for nephrocalcinosis, eye exam for cataracts, CT head imaging (in patients with neurological findings) for calcifications, regular dental care, and management of comorbid endocrinopathies. A multidisciplinary approach is needed in this complex, heterogeneous group of disorders.

<![CDATA[SAT-333 Autoimmune Polyglandular Syndrome Type 1 in a Patient with Bipolar Disorder]]> Autoimmune Polyglandular Syndrome Type 1 (APS-1) is clinically defined as the presence of at least two components of the classic triad of hypoparathyroidism, adrenal insufficiency and mucocutaneous candidiasis. It is commonly seen amongst Finns, Sardinians and Iranian Jews and is a very rare condition, with a challenging set of management.

50-year old female with a known past medical history of Bipolar disorder, Primary Adrenal Insufficiency, Hypothyroidism, Alopecia was transferred from an acute psychiatric facility for medical clearance. Patient was noted to have findings initially suggestive of Subarachnoid Hemorrhage on a CT scan of the Head which was later deemed to be likely dystrophic calcification. During her stay on the medical floors, patient was found to be unresponsive and hypotensive, after a bout of agitation. She had to be urgently intubated and started on stress doses of steroids (Hydrocortisone 100 mg every 8 hours) and was upgraded to the Intensive Care Unit (ICU). Patient was eventually successfully weaned off the ventilator and steroid doses were slowly tapered. During her hospital course she was noted to have gradually decreasing Calcium levels, down to a corrected Calcium level of 7.6. Further workup for the hypocalcemia revealed a Vitamin D Level of 12, and Parathyroid Hormone (PTH) level of 0. Patient was subsequently started on adequate Calcium and Vitamin D supplementation for the same. After a few days when the family was located and contacted through social work support, and a more thorough history was obtained, it was found that one out of the patient’s three sisters had a similar constellation of deficiencies. Patient had previously been diagnosed with a polyendocrine syndrome, however she was irregular with her medication compliance and follow-up outpatient with her endocrinologist due to her persistent psychiatric issues and poor social support.

APS-1 is an autosomal recessive disorder caused by mutation in AIRE, the autoimmune regulator gene which is hypothesized to be playing an important role in the generation of regulatory T cells. Although the complete pathogenesis is unclear, mutation in generation of these regulatory cells leads to autoantibody formation. Hypoparathyroidism or Chronic persistent Mucocutaneous Candidiasis is usually the first manifestation seen during adolescence and adrenal insufficiency usually manifests later. A variation of other autoimmune syndromes can be observed, with Hypothyroidism, Type-1 Diabetes Mellitus and Primary Hypogonadism being a few of them. Treatment primarily involves replenishment of the hormones of the underperforming gland. Management of a complex syndrome like APS-1 in a patient with psychiatric disabilities can be challenging and needs a multi-disciplinary approach involving the endocrinologist, the primary care physician and the psychiatrist.

<![CDATA[SAT-378 Posterior Reversible Encephalopathy Syndrome Associated with Malignant Hypercalcemia and Hypertension Due to Primary Hyperparathyroidism]]> Background

Posterior Reversible Encephalopathy Syndrome (PRES) is an acute neurological entity characterized by headache, altered mental status, visual loss and seizures. It can be triggered by multiple aetiologies including hypertension, eclampsia, cytotoxic and immunosuppressant drugs and, rarely, hypercalcaemia.

Case Report

A 64 years old woman presented with five weeks history of fatigue, poor appetite, dry mouth, constipation and abdominal discomfort and one-week history of nausea and vomiting. She was hypertensive at 177/88 mmHg with dry mucous membranes. Physical examination and neurological examination were unremarkable.

Laboratory investigation showed corrected calcium of 4.83 mmol/L (2.25-2.54) with

Ionized calcium of 2.62 mmol/L (1.15-1.27), parathyroid hormone (PTH) of 1330 ng/l (15-68), phosphate of 1.16 mmol/L(0.8-1.5), magnesium of 0.51 mmol/L (0.7-1.0) urea of 10.7 mmol/L (2.8-8.4), creatinine of 119 umol/L (49-90), potassium 3.4 mmol/L(3.5-5.1). She was aggressively rehydrated, commenced on Intravenous (IV) frusemide and was given IV zoledronic acid. Cinacalcet was commenced and titrated gradually up according to corrected calcium level (target corrected calcium level between 2.5-3.0 mmol/L).Electrolytes deficiencies corrected with replacement therapy.Ultrasound neck and parathyroid MIBG scan showed large 5.1cm heterogeneous lesion posterior to the right lobe of the thyroid extending inferiorly into the superior mediastinum consistent with parathyroid mass. Histology confirmed benign parathyroid adenoma.

38 hours after admission, the patient became intermittently confused and complained of visual symptoms followed by complete visual loss in the left eye. This was followed shortly by status epilepticus which required treatment with intravenous antiepileptic therapy and mechanical ventilation.Corrected calcium at that time was 3.82 mmol/L.Patient was noted to have left upper limb weakness.Computed tomography of the brain was normal and magnetic resonance imaging (MRI) of the brain showed bilateral symmetrical subcortical T2 hyper- intensities in the occipital- parietal lobes consistent with PRES.

By day five, corrected calcium was 2.52 mmol/L. On day six patient had successful parathyroidectomy. Post operatively PTH was 7.73 ng/L and corrected calcium 2.27 mmol/L. Repeated Brain MRI showed resolution of symmetrical subcortical T2 hyperintensities within both occipital lobes. She made a complete neurological recovery. DEXA scan showed osteoporosis (T score in left forearm of -3.8). She was commenced on bisphosphonate therapy.

In conclusion, we demonstrated hypercalcemia-induced PRES. This can be a life-threatening condition and can be reversed by proper treatment of hypercalcemia.

<![CDATA[SAT-376 Secondary Hyperparathyroidism, an Untoward Complication of High Dose Phosphate Supplementation in Hereditary Hypophosphatemic Rickets]]> Background: Hereditary hypophosphatemic rickets is a debilitating disease with multiple skeletal abnormalities. Children exhibit rickets and growth failure, while adults exhibit bone pain, enthesopathy, HTN, and arthritis. Gene mutations involving renal phosphate reabsorption(PHEX, FGF23, SLC34A3) leads to renal phosphate wasting. Modes of inheritance include X-linked dominant (most common), autosomal dominant, and autosomal recessive. High dose oral phosphate supplements along with calcitriol are the mainstay of treatment. This can lead to complications of secondary hyperparathyroidism. Clinical Case: An 81-year-old Caucasian woman with PMH of X-linked dominant hypophosphatemic rickets (XLH), secondary osteoarthritis of both knees, HTN, and neuropathy was seen in the Endocrinology clinic. She was diagnosed with XLH 47 years ago and was taking calcitriol 0.5 mcg daily along with a phosphate supplement of 250 mg, 2 tablets 5 times a day. She underwent multiple corrective orthopedic procedures and bilateral knee replacements. On exam, she had short stature (height of 149.9 cm), arthritic changes of bilateral hand joints, and dentures. Starting in 2015, there was a rise in PTH to 101 pg/ml (normal 18.4-80 pg/ml). Over the next 4 years her PTH continued to rise to 182.6 pg/ml, 244.4 pg/ml, 350.6 in 2016, 2017, and 2019 respectively. A 24-hour urine collection revealed a calcium level of 175 mg (normal 100-250 mg/24 hours) and a phosphorus level of 2191 mg (normal 900-1300 mg/24 hours). In December of 2018, she developed hypercalcemia with a serum calcium level of 10.9 mg/dl(normal 8.5-10.5 mg/dl). We then tapered off calcitriol and decreased the phosphate supplements to TID. Despite these measures, her PTH continued to rise, but phosphorus remained normal. A Sestamibi scan showed hyperplasia of all four parathyroid glands, and a DXA scan showed normal bone mineral density. Serum alkaline phosphatase was normal. We decreased her phosphate supplements to BID and started cinacalcet at 30 mg BID. Conclusion: This case illustrates the challenges of primary and secondary hyperparathyroidism when treating XLH. It is proposed that an increased oral phosphate load transiently lowers ionized calcium in serum, which then stimulates PTH secretion. Increased mineralization of bone is another possible explanation of this phenomenon. Persistent parathyroid stimulation can cause hyperplasia of parathyroid glands, nephrocalcinosis, hypertension, and renal failure. Early identification, temporary discontinuation of oral phosphate, and an increase of calcitriol will lower PTH. The FDA approved burosumab for the treatment of XLH in 2018. Future studies are needed to see if burosumab therapy prevents the above complications associated with traditional treatment.

<![CDATA[SAT-368 CYP24A1 Mutation Masking Malignancy Mediated Hypercalcemia]]> Background: Mutations in CYP24A1, resulting in reduced conversion of 1,25(OH)2D to its inactive metabolite 24,25-(OH)2D3,are rare causes of parathyroid hormone (PTH)-independent hypercalcemia. While manifestations may range from the severe idiopathic infantile hypercalcemia due to biallelic mutations, heterozygous loss-of-function mutations causing milder phenotypes are increasingly reported in adults. Elevated 1,25(OH)2D and hypercalciuria often accompanied by a history of nephrolithiasis are characteristic. Worsening hypercalcemia, under conditions such as pregnancy or sunlight exposure that enhance 1,25(OH)2D and 25(OH)D production, respectively, has been described in CYP24A1 mutations. We describe a patient with hypercalcemia and a history of lymphoma who was found to have elevated 25-OH-D3 and low 24,25-(OH)2D3 levels, suggesting a mutation in CYP24A1. Clinical Case: An 80 year-old Caucasian male with history of indolent non-Hodgkin lymphoma diagnosed in 2016,well controlled after several courses of chemotherapy,was referred for recurrent hypercalcemia. Laboratory studies showed levels of 1,25(OH)2D of 78 (18–72 pg/mL) and PTH 22 (10–65 pg/mL) with calcium ranging from 10.3 to 12.6 (8.5–10.1mg/dL), an undetectable PTHrP, 25(OH)D level of 32.9 (30–100 ng/mL), and 24-hour urinary calcium of 378mg. He was treated with high dose prednisone for presumed 1,25(OH)2D-mediated hypercalcemia. Despite initial good response, hypercalcemia became progressively difficult to control requiring escalating doses of steroids. Repeat 1,25(OH)2D levels improved to 30–40 pg/mL, but subsequently rebounded to >150. Oncologic re-evaluation found low-grade follicular lymphoma in inguinal lymph nodes,which were thought to be the source of 1,25(OH)2D overproduction. Detailed history and records review, however, revealed that onset of hypercalcemia dated back to 2006, concurrent with the development of several episodes obstructive uropathy due to stones. These events preceded the diagnosis of lymphoma by a decade, and resulted in CKD stage 4. Family history is notable for nephrolithiasis in his fatherand son. We suspected CYP 24A1 mutation. Vitamin D metabolite analysis demonstrated a 25-OH-D3 of 27 (20-50ng/mL) and 24,25-(OH)2D3 of 0.56 ng/mL with a ratio elevated to 48.21 (<25), indicative of a defect in vitamin D degradation that potentially exacerbates oversupply of 1,25(OH)2D, mediated via its reduced metabolism. Genetic evaluation is in progress. After initiation of treatment with Rituximab, his serum calcium levels declined along with regression of his lymphoma. Conclusion: Although mutations in CYP24A1 are an uncommon cause of hypercalcemia, they should be considered in the differential diagnosis of elevated 1,25(OH)2D levels without a clear source, as confirming this diagnosis strongly impacts treatment decisions and clinical outcome.

<![CDATA[SAT-335 New Onset Adult Idiopathic Primary Hypoparathyroidism Concomitant with Severe Aplastic Anemia]]> Introduction: Primary hypoparathyroidism is a relatively rare cause of hypocalcemia with cases of primary hypoparathyroidism in the US estimated at 24–37 per 100,000 with 75% being due to neck surgery and 25% due to non-surgical causes. The clinical presentation depends on the acuity of development of hypocalcemia and the absolute level of serum calcium. Here is a case of severe hypocalcemia secondary to hypoparathyroidism of unknown etiology followed by the development of severe aplastic anemia.Case report: A 60-year-old Caucasian male presented to our ED with fatigue, tingling, numbness in extremities and was found to have severe hypocalcemia at 6.8 mg/dl and decreased PTH at 11 pg/mL. Calcium levels 8 months prior to presentation were normal. No history of neck surgery, radiation exposure or family history of autoimmune disorders. Initial workup included creatinine, magnesium and TSH were normal. Autoimmune panel (including PTH Abs and CaSR Abs), HIV test, hepatitis panel, serum protein electrophoresis were also negative. Infiltrative causes of hypoparathyroidism including hemochromatosis, malignancy and granulomatous diseases like sarcoidosis were ruled out with tissue sampling and lab workup. Sestamibi scan obtained showed no parathyroid activity in all four glands. Patient was initially treated with IV calcium to improve serum calcium to more than 7.5mg/L and then switched to oral calcium carbonate 500mg TID and calcitriol 0.5mcg BID until the calcium level was brought up to the lower limit of normal. Patient was seen in follow up and was doing well without any adverse effects. Consequently, the patient developed severe aplastic anemia which was treated with steroids and interestingly, has caused a gradual but consistent increase in PTH levels.Discussion: Idiopathic hypoparathyroidism (IHP) is a rare condition with an incidence of 0.02%. IHP can occur sporadically or as part of a familial condition with autosomal dominant, recessive and X-linked recessive patterns. Certain autosomal forms of hypoparathyroidism have mutations in the PTH gene and Calcium-Sensing Receptor (CaSR) gene. The challenging nature of this case is due to the subacute nature of the patient’s presentation along with the lack of a definitive etiology. The patient’s negative family history and older age makes genetic causes less likely, and Abs against PTH and CaSr were also negative. The patient’s diagnosis of severe aplastic anemia has made the case more fascinating, especially since its management with steroids has causes an improvement in the patient’s PTH status. Regardless of etiology, primary hypoparathyroidism is treated with lifelong supplementation of calcium and calcitriol to a goal serum calcium level at the lower limit of normal. Reference: Abate EG,Clarke BL. Review of Hypoparathyroidism. Front Endocrinol (Lausanne). 2017; 7:172. Published 2017 Jan 16

<![CDATA[SAT-340 Familial Hypocalciuric Hypercalcemia Due to a C.571G&gt;A (p.Glu191Lys) Variant in the GNA11 Gene]]> Background: Familial hypocalciuric hypercalcemia (FHH) type 1 is caused by inactivating pathogenic variants in the calcium sensing receptor (CASR) gene and clinically presents with serum hypercalcemia, low urine calcium excretion, and inappropriately normal PTH response. In a minority of patients with CASR-negative FHH (up to 26%), variants in AP2S1 are linked to FHH type 3. Similarly, inactivating pathogenic variants in the GNA11 gene have been shown to cause FHH type 2 in up to 10% of CASR and AP2S1 negative cases.1

Clinical case: A four-month old male presented to the ED for symptoms of polyphagia and polyuria. Biochemical evaluation found a serum calcium of 11.9 mg/dL (8.7-11.0 mg/dL), magnesium 2.4 mg/dL (1.6-2.3 mg/dL), 25-OH Vit D 38 ng/mL (30 -100 mg/dL) and intact PTH 27.8 pg/mL (15-65 pg/mL). His further labwork fit clinically with FHH with a urine calcium-creatinine ratio < 0.09 (<= 0.20), accompanied by a serum calcium level of 11.9 mg/dL and iCal of 1.48 mmol/L (1.13 – 1.37 mmol/L). Subsequent monitoring of serum calcium levels showed improvement with time, along with improvement in polyphagia and polyuria.

Of note, mother also has a history of hypercalcemia that was diagnosed at age fifteen as part of a rheumatology evaluation. At diagnosis, her calcium was 12.1 mg/dL (9.3-10.6 mg/dL), Mg 2.3 mg/dL, phosphorous 3.3 mg/dL (2.3-4.8 mg/dL), intact PTH 39 pg/mL, and urine calcium-creatinine ratio of 0.04 (<= 0.20). She was treated with calcitonin, during which she developed hypercalciuria with elevated PTH of 88 pg/mL. A parathyroid uptake scan was concerning for adenomatous changes in the right upper parathyroid gland, but she was subsequently lost to follow-up without additional evaluation.

Sequencing of the AP2S1, CASR, CDC73, CYP24A1, GCM2, GNA11, MEN1, PTH1R, or SLC34A1 genes by Next-generation sequencing methodology was completed in the patient and only revealed a maternally inherited missense variant of unknown significance of c.571G>A (p.Glu191Lys) in GNA11. This G to A transition in exon 4 substitutes a glutamic acid for a lysine at codon 191 of a highly conserved amino acid. This variant has not been previously reported in affected individuals nor has it been observed in the healthy population per the gnomAD population database. It is predicted to be deleterious/probably damaging by in silico tools (SIFT, PolyPhen2).

Conclusion: To our knowledge, this is the first case demonstrating the presence of a c.571G>A (p.Glu191Lys) variant in the GNA11 gene, in a child with familial hypocalciuric hypercalcemia as well as in his affected mother. In cases with strong suspicion of FHH despite negative CASR and AP2S1 analyses, genetic analysis of GNA11 should also be considered.


(1) Hovden, S., Rejnmark, L., Ladefoged, S., & Nissen, P. (2017). AP2S1 and GNA11 mutations – not a common cause of familial hypocalciuric hypercalcemia, European Journal of Endocrinology, 176(2), 177-185.

<![CDATA[SAT-336 An Unusual Case of Symptomatic Hypercalcemia from Graves’ Disease in a Young Filipino Female]]> Hypercalcemia in hyperthyroidism is usually asymptomatic, and related to a concurrent primary hyperparathyroidism. In this report, we describe a case of symptomatic hypercalcemia secondary to Graves’ disease alone. Case Report. A 24-year-old Filipino female presented to the emergency department with generalized weakness, vomiting and abdominal pain. No other symptoms were noted. She was otherwise previously healthy. Family history was unremarkable. During physical exam, she was noted to have a non tender palpable thyroid gland without bruit. Her ECG showed sinus tachycardia. The complete blood count and electrolytes were normal however, ionized calcium was high at 1.6mmol/L (NV 1–1.3). Renal function was normal. Hydration with saline and Furosemide 20mg once daily was started though calcium levels remained elevated. Other causes of hypercalcemia were excluded as PTH was appropriate suppressed (8.8ng/L; NV 14–72), vitamin D was also suppressed (15.29nmol/L; NV >30). CT scan of chest and abdomen and bone scan did not point to any underlying malignancy nor metabolic bone disease. Medication history was also unremarkable. She was hyperthyroid with a suppressed thyroid stimulating hormone level of 0.004pmol/L (NV 0.55–4.78), free T3 of >20pmol/L (NV 2.3–4.2), free T4 of 8.4pmol/L (NV 0.89–1.76). Thyroid receptor antibody levels were raised at 41.07kU/L (NV <1) supporting the diagnosis of Graves’disease. She was started on propylthiouracil 50mg four times daily, along with propranolol 40mg three times daily. She was subsequently seen after two weeks with normal repeat calcium level and thyroid function test. Conclusion. This report aims to highlight that thyroid disease should always be considered as a cause of hypercalcemia. A concomitant primary hyperparathyroidism should also be evaluated. The definitive treatment for the hypercalcemia is correction of thyroid function.

<![CDATA[SAT-LB64 Teriparatide and Its Bone Healing Power]]> Introduction:

Teriparatide, a parathyroid hormone analog, is an important anabolic agent approved by the U.S. Food and Drug Administration to increase bone mineral density in osteoporotic patients. Parathyroid hormone (PTH) regulates calcium, phosphate, and active vitamin-D metabolites.The amino terminal peptide fragments of PTH has been known to increase bone mass and are being used in clinical practice for osteoporosis management (1).

Current literature shows the efficacy of teriparatide in increasing bone density of lumbar spine and femoral neck, and decreasing the risk of vertebral and non-vertebral fractures both in postmenopausal women and men. It is also known to prevent fractures in patients with osteoporosis and promote healing of fractures (2).

Case Description:

A 79-year-old Hispanic female with history of osteopenia and major lumbar spine wedge compression fractures presented to our clinic for consultation. She was on ibandronate for the past four months and was having symptoms of pill esophagitis. Her last bone mineral density done on August 2017 revealed T-score of -2.5 at the lumbar spine, -1.5 at the left femoral neck, and 3.3% bone loss on the left femoral head. Rather than being started on teriparatide, zoledronic acid, or denosumab, she continued ibandronate along with calcium and vitamin D. Two months after the initial consultation, she sustained a traumatic fracture of the posterior arch and body of C2 bilaterally following a motor vehicle accident. There were discussions about starting anabolic treatment, as serial imaging did not show any significant improvement in the healing process despite the use of a collar. Two months after sustaining C2 fracture, she was started on teriparatide. Repeat cervical spine x-ray three months later showed complete healing of the C2 fracture.


There are a limited number of cases reported in regards to teriparatide induced healing of non-osteoporotic fractures (3). Our case is one of the very few reported to have shown complete radiographic and clinical healing of a traumatic, non-osteoporotic fracture after use of teriparatide for 12 weeks.

<![CDATA[SAT-357 First Case in Saudi Arabia Revealing Fahr Syndrome Secondary to Hypoparathyroidism: A Case Report]]> Introduction: Fahr Syndrome is a rare inherited or sporadic neurological disorder. It is characterized as in abnormal calcium deposition or in other words, calcification in the brain which almost always occurs bilaterally. Patients with Fahr syndrome usually presents with neurological symptoms such as seizures, tetany, speech impairment, dementia, deterioration of intelligence, involuntary movements. The etiology of Fahr syndrome is mostly associated with endocrine disorders especially hypoparathyroidism either primary or secondary or pseudo hyperparathyroidism; including adult onset neurodegenerative conditions, infectious disease like intrauterine and perinatal infections or inherited congenital causes are also considered.

Clinical Case The authors report a 33-year-old Ethiopian female not known to any medical illness presented with abnormal involuntary left-hand movement, headache and dizziness. Further examination shows positive Chvostek’s and Trousseau’s signs. In addition, laboratory findings reveal decreased levels of serum calcium (1.227 mmol/L, normal range of 2.2-2.65 mmol/L), serum albumin (33.53 mg/dL, normal range of 35-52 g/L) and parathyroid hormone (0.3pmol/L, normal range of 1.1-8.43 pmol/L), decreased vitamin D serum level (14.52 ng/ml, normal range of 30-75 ng/ml). Interestingly, brain imaging shows bilateral symmetrical subcortical white matter, basal ganglia, cerebellar dentate nuclei calcifications. Thus, Fahr syndrome diagnosis was made. She was promptly treated with calcium and vitamin D replacement. Calcium gluconate was given intravenously with oral calcium carbonate and oral cholecalciferol. The patient recovered with this treatment leading to positive results without any recurring symptoms.


Conclusion In conclusion, Fahr syndrome is a rare sequel of hypoparathyroidism, mostly presented with neurological symptoms due to hypocalcemia which after correction subdues the occurring manifestation such as in this case presented. Early diagnosis of Fahr syndrome due to hypoparathyroidism is crucial for prompt treatment and reversal of symptoms also to prevent complications.


<![CDATA[SAT-381 Adjunct Benefit of Aquatic Therapy in Juvenile Hypophosphatasia Initiated in an Adult]]> Background: This is a case of improvement in visual analog scale pain rating and objective functional capacity in juvenile hypophosphatasia (HPP) following treatment with asfotase alfa and adjunct physical therapy (PT) performed in an aquatic environment. Clinical Case: A 45-year-old female with a history of psoriatic arthritis and osteoarthritis was referred for low serum alkaline phosphatase (ALKP) (<10 U/L). Her history of eight fractures over the preceding 25 years including bilateral femur nonunion repaired with rods eight years prior to presentation led to a diagnosis of juvenile HPP, and asfostase alfa was ordered. She is ambulatory only with a rolling walker from a deficit in dynamic standing balance and chronic pain. Referrals were made for both PT and pain management for these symptoms. The initial PT evaluation established reasonable goals to include the performance of in-home exercise, increase strength and range of motion, decrease pain, improve standing balance, and progress from walker to cane. Aquatic therapy was chosen in order to reduce patient’s effective weight. The right hip complex, lumbar spine, and left leg were chosen as areas of focus based on pain reports. A four-week follow-up evaluation by the therapist reported patient had been performing at home exercises. Pain scale reports of the lumbar spine, right hip, and left leg were within the moderate range and near or meeting the patient’s self-reported least pain experienced. Goniometric measurements of the right hip showed range of motion improvements averaging 9%. The lumbar spine’s range of motion increased an average of 18%. Discussion: HPP is capable of creating severe disability, and its rarity has led to a dearth of investigation into appropriate treatment. Recommendations have been made previously for PT in children and infants presenting with juvenile or infantile HPP; this case suggests these recommendations are applicable to adults as well. The mechanisms of these improvements remain unclear; however, evidence exists that weight-bearing exercise may result in increased levels of bone-specific isoforms of ALKP. This endogenous path to increased serum ALKP may play a role in potentiating the effects of asfostase alfa. 1. Shapiro JR, Lewiecki EM. Hypophosphatasia in Adults: Clinical Assessment and Treatment Considerations. Journal of Bone and Mineral Research 2017;32(10):1977–1980. 2. Phillips D, Case LE, Griffin D, Hamilton K, Lara SL, Leiro B, Monfreda J, Westlake E, Kishnani PS. Physical therapy management of infants and children with hypophosphatasia. Molecular Genetics and Metabolism 2016;119(1–2):14–19. 3. Rudberg A, Magnusson P, Larsson L, Joborn H. Serum Isoforms of Bone Alkaline Phosphatase Increase During Physical Exercise in Women. Calcified Tissue International 2000;66(5):342–347.

<![CDATA[SAT-358 Hypercalcemia-Induced Altered Mental Status as the Primary Manifestation of Classic Hodgkin Lymphoma]]> Hodgkin lymphomas (HL) are lymphoid neoplasms formed by a conglomerate of malignant Hodgkin/Reed-Sternberg cells with heterogeneous non-neoplastic inflammatory cells. Classic HL (cHL), one of two major subtypes, comprises 90% of all cases. HL typically presents as asymptomatic adenopathy or mass on chest imaging; constitutional symptoms (unintentional weight loss, night sweats, fever) occur in approximately 40% of cases. Though hypercalcemia is not uncommon in HL due to increased production of 1,25(OH)2D or, less commonly, direct bony involvement, it is unusual for severe hypercalcemia and its related symptoms to be the primary reason for presentation such as in our case below.

An 87-year-old man was admitted to our institution with three days of increasing agitation and confusion in the context of several weeks of forgetfulness and decline in his daily activities. He previously lived robustly independently. His past medical history included atrial fibrillation, hyperlipidemia, and benign prostatic hyperplasia. His home medications included metoprolol, apixaban, atorvastatin, tamsulosin, finasteride and a multivitamin.

Laboratory evaluation revealed serum calcium 17.5 mg/dL and serum creatinine 3.0 mg/dL (eGFR 20 mL/min/1.73m2). Complete blood count, phosphate, magnesium and alkaline phosphatase were normal. Intravenous fluids and later pamidronate improved his calcium to the 11–13 mg/dL range. Endocrinological workup revealed PTH 7 pg/mL (nl 15–65 pg/mL), 25(OH)D 15 ng/mL (nl 20–80 ng/mL), PTHrP 0.8 pmol/L (nl <2.0 pmol/L) and 1,25(OH)2D 57 pg/mL (nl 18–64 pg/mL). Serum protein electrophoresis showed no abnormalities and lactate dehydrogenase was 230 U/L (nl 125–250 U/L)

Computed tomography (CT) of his abdomen revealed non-specific prominent mesenteric lymph nodes. Neck CT did not show any abnormal cervical or supraclavicular lymphadenopathy. Chest CT did not show any mediastinal masses, abnormal lymphadenopathy, or findings consistent with silicosis (he had a 15-year history of masonry and brick-laying). Bone scan showed asymmetric uptake in two areas of his femurs, with xrays revealing subcortical scleroic lesions. Patient declined inpatient bone marrow biopsy, and was empirically started on prednisone, with rapid improvement in calcium to 9.6 mg/dL and return to his baseline mental status. He eventually accepted and underwent bone marrow biopsy as an outpatient, which revealed marrow involvement by classic Hodgkin lymphoma. The patient was started on a regimen of brentuximab vedotin plus doxorubicin, vinblastine, and dacarbazine, with excellent clinical response.

This case illustrates an atypical, hypercalcemia-driven initial presentation of Hodgkin’s lymphoma. It also exhibits the hallmark “inappropriate normal” 1,25(OH)2D which, in the context of hypercalcemia and low PTH, suggests extrarenal (i.e. PTH-independent) production of 1,25(OH)2D.

<![CDATA[SAT-367 A Case Series: Discovery of Parathyroid Carcinoma During Parathyroidectomy for Primary Hyperparathyroidism]]> Introduction: Parathyroid carcinoma is rare and represents <1% of patients diagnosed with hyperparathyroidism (1).

Clinical Cases: We present two cases of incidentally diagnosed parathyroid carcinoma during parathyroidectomy for primary hyperparathyroidism.

A 69-year-old female was referred for hypercalcemia of 10.7 mg/dL (normal range 8.4-10.2). She had bone pain, fatigue, and mild depression. She was taking triamterene-hydrochlorothiazide, vitamin D 2000 international units daily, and 1 caltrate daily. Her thiazide diuretic was discontinued, and a repeat calcium was 9.5 mg/dL with a PTH of 79 pg/mL (normal range 14-64). Vitamin D and renal function were normal. A 24 hour urine calcium was elevated at 706 mg/24 hours (normal range 100-321). A bone density revealed osteopenia.

Based on the high urine calcium, a thyroid ultrasound was completed and showed an enlarged right parathyroid gland. Intraoperatively, the surgeon found a superior parathyroid gland adherent to the local soft tissues with recurrent laryngeal nerve entrapment. The right superior parathyroid and right thyroid lobe were resected. Pathology demonstrated an infiltrating parathyroid carcinoma. Postoperative monitoring has included: calcium, creatinine, PTH and neck ultrasound every six months without evidence of recurrence.

A 79-year-old man was referred for an approximate 18-month history of hypercalcemia. He had a prior kidney stone and constipation. He was not on calcium supplementations or thiazides. On lab testing calcium was 11.0 mg/dl with prior levels of 11.7 mg/dl. PTH was 246 pg/ml and vitamin D was 20.1 ng/ml (normal range 30-80). Imaging was obtained for parathyroid localization. A neck ultrasound and nuclear medicine study showed a right inferior parathyroid adenoma. A bone density revealed osteoporosis. Intraoperatively, the surgeon found a bilobed parathyroid extending intrathyroidal and adherent to the recurrent laryngeal nerve. The right inferior parathyroid, right thyroid lobe, and isthmus were resected. Pathology was consistent with parathyroid carcinoma. The patient had recurrent laryngeal nerve damage with persistent hoarseness postoperatively.

Clinical Lessons: Patients with parathyroid carcinoma typically present with symptomatic hypercalcemia with mean levels of 13.5-14 mg/dL and mean PTH values 8.7 times the upper limit of normal (1). Given the rarity of the condition, there are no guidelines for surveillance (1). These cases highlight atypical, mild, and early presentations of an unusual and typically aggressive disease and serve as an example of how to monitor for recurrence.

Reference: 1- Stack BC, Bodenner DL. Medical and Surgical Treatment of Parathyroid Diseases An Evidence-Based Approach. Switzerland: Springer, Cham; 2017.

07/978-3-319-26794-4_31#enumeration. Accessed November 3, 2019.

<![CDATA[SAT-LB65 A Rare Existence]]> Primary hyperparathyroidism is a common endocrine disorder of metabolism usually due to a parathyroid adenoma. Although, the clinical presentation of primary hyperparathyroidism has changed from Albright’s description of a disease of bones and stones, the central target organs affected by this disorder continue to be the skeleton and kidneys. With the advent of routine biochemical screening, the typical diagnosis of primary hyperparathyroidism is no longer accompanied by overt skeletal and renal involvement. Majority of the cases of primary hyperparathyroidism are due to parathyroid adenomas. Giant glands were defined as greater than the 95th percentile, characterized as glands weighing > 3.5 grams.

This present case in a 54-year old female is a rare case of primary hyperparathyroidism secondary to a giant parathyroid adenoma measuring 10.7 x 8.0 x 40.0 cm and weighing 145 grams, the largest giant parathyroid adenoma reported to date, with co-existent silent thymoma, multinodular goiter and osteosclerosis of the vertebral spine, metaphorically known as the “rugger-jersey spine”. The association between thymoma and parathyroid adenoma is rare, and only 3 cases have been reported in the literature. We characterized the correlation of preoperative imaging, intraoperative location, and postoperative course, including significant postoperative hypoparathyroidism, as compared to other patients with PHPT to determine whether giant adenomas represent a clinical entity with distinct clinical characteristics.

Keywords: primary hyperparathyroidism, giant parathyroid adenoma, rugger-jersey spine, thymoma



Primary hyperparathyroidism

<![CDATA[SAT-371 Severe Hypocalcemia Secondary to Pseudohypoparathyroidism]]> Introduction: Pseudohypoparathyroidism (PHP) is a rare disorder characterized by PTH resistance due to a mutation in the GNAS gene causing decreased cyclic AMP generation. The 5 subtypes of PHP include type 1a, 1b, 1c, 2, and pseudo-PHP with type 1a being the most common. Patients with PHP present with hypocalcemia, hyperphosphatemia, appropriately elevated PTH, and suppressed calcitriol levels. PHP type 1a patients have characteristic features including obesity, short stature, round facies, and shortened metacarpals. PHP patients should be evaluated for other endocrinopathies as mutations in the GNAS gene may result in resistance to other hormones like TSH, GHRH, and gonadotropins.

Case Report: This patient is a 25 year old male who presented to clinic for evaluation of hypocalcemia. He denied any personal or family history of calcium disorders, thyroid disease, or parathyroid disease. He admitted to severe fatigue and muscle cramps for over one year leading to a car accident. He was sent to the emergency room and diagnosed with hypocalcemia requiring IV calcium gluconate. He was then seen by his family physician and was found to have elevated intact PTH and low 25-hydroxy vitamin D levels. He was placed on cholecalciferol 5000 international units (IU) daily, ergocalciferol 50,000 IU once weekly, calcium carbonate 500 mg (6 tablets daily), and referred to endocrinology. The physical exam was unremarkable. The laboratory values tested were an intact PTH of 645 pg/mL (10–65 pg/mL), ionized calcium of 4.2 mg/dL (4.6–5.08 mg/dL), magnesium of 2.1 mg/dL (1.5–2.3 mg/dL), 25-OH vitamin D of 31.7 ng/mL (20–100 ng/mL), and creatinine of 0.81 mg/dL (0.7–1.3 mg/dL) four months after starting the above mentioned calcium and vitamin D supplementation. Further testing revealed a phosphorus level of 4.8 mg/dL (2.3–4.7 mg/dL), calcitriol level of 55.8 pg/mL(19.9–79.3 pg/mL), TSH of 10.46 uIU/mL (0.4–4.2 uIU/mL) and free T4 of 1.5 ng/dL (0.8–1.7 ng/dL). His labs were consistent with PHP. Although unknown which PHP subtype, it is likely not type 1a as he lacks its characteristic phenotype. His abnormal thyroid function tests may be secondary to TSH resistance associated with the GNAS gene mutation. He was told to continue the current dose of calcium carbonate but to discontinue ergocalciferol and cholecalciferol. He was placed on calcitriol 0.5 mcg daily. He will have repeat levels of his ionized calcium, calcitriol, TSH, and free T4 in two weeks. If TSH is still above 10 uIU/mL, we will start levothyroxine replacement.

Conclusion: Although a rare disorder, clinicians should have a high index of suspicion for PHP to prevent complications of hypocalcemia (tetany, arrhythmias, seizures) and metabolic bone disease from PTH resistance.

References: Mantovani, G. Pseudohypoparathyroidism: Diagnosis and Treatment, The Journal of Clinical Endocrinology & Metabolism, Volume 96, Issue 10, 1 October 2011, Pages 3020–3030.

<![CDATA[SAT-372 A Case of Hypercalcemia Secondary to Rhabdomyolysis Induced by Heroin Use]]> Background: Rhabdomyolysis is a potential life threatening condition defined as injury of the skeletal muscle, which results in the release of intracellular contents into the circulation. This muscle injury is often associated with the development of myoglobinuria, electrolyte abnormalities, and often ARF; it can be caused by diverse mechanisms including drugs and toxins. We present a case of rhabdomyolysis complicated by hypercalcemia and ARF in a patient with a history of polysubstance abuse after using intravenous heroin.

Case: A 28 y/o male with h/o polysubstance comes to the ED with c/o fatigue, nausea, vomiting and decreased urine output for about 5 days; patient acknowledged using heroin and afterwards he developed weakness and tenderness in upper and lower extremities. Additionally he admitted cocaine and marijuana abuse. On physical exam vital signs were unremarkable and he had some mild tenderness to palpation mostly of the quadriceps bilaterally. Laboratory data was significant for acute kidney injury (cr 11.33 mg/dl, n: 0.7–1.5 mg/dl) and CPK 171920 u/l (n: 22–269 u/l). He received 2 L of NS in the ED and was started on NS at 100cc/hour.

He underwent hemodialysis on day 2; initially he was treated for hypocalcemia with calcium and vitamin D supplementation until day 11 were hypercalcemia (calcium 12.7 mg/dl, n: 8.7–10.3 mg/dl; ionized calcium 1.7 mmol/l, n: 1.12–1.32) was noted; this was associated with concomitant suppression of PTH (5 pg/ml, n: 10–65 pg/ml). He remained asymptomatic from calcium abnormalities during his hospitalization, his urine output recovered progressively, hemodialysis was discontinued on day 13. Upon discharge was recommended to f/u with nephrology.

Discussion: Various neurological and neuromuscular complications of heroin abuse have been described; one of these is rhabdomyolysis; its pathophysiology in heroin abuse is thought to be multifactorial; including acidosis, hypoxia, muscle compression and adulterants found in heroin. Narcotics may also have direct cell toxicity and alter membrane transport. Usually upon initial presentation hypocalcemia is one of the most common electrolyte imbalances seen with rhabdomyolysis. The proposed mechanism is precipitation of serum calcium salts in necrotic muscle. This may be followed by hypercalcemia during the diuretic phase of ARF which appears to be a relatively unusual complication associated with the presence of severe muscle damage due to metastatic calcium salts that are liberated from the necrotic muscle and the return to the serum.

Conclusion: This case report highlights the importance of recognizing potential electrolyte imbalances in patients with rhabdomyolysis; it appears, that concomitant rhabdomyolysis and ARF are needed for a patient to develop hypercalcemia.

Serum calcium should always be routinely measured and the appropriate treatment should be implemented to improve outcomes.

<![CDATA[SAT-339 Calcium Level in a Patient with Rhabdomyolysis. A Tale of Two Phases]]> Background: Calcium kinetics can be challenging during the different phases of rhabdomyolysis1. We herein report a case of sever hypercalcemia refractory to hemodialysis following a period of hypocalcaemia that developed in a patient with rhabdomyolysis.

Case: A 27-year-old male patient was diagnosed with meningoencephalitis complicated with septic shock, continuous seizures, rhabdomyolysis, acute kidney injury and oliguria. His creatinine was 219 μmol/L (53–115), urea was 8 mmol/L (2.5–6.4). Creatine kinase (CK) was significantly high above assay range. Corrected serum calcium was 1.82 mmol/L (2.12- 2.52), phosphate was 0.48 mmol/L (0.81–1.58). He required intermittent sessions of hemodialysis and antibiotics therapy which both have been initiated since the first day of admission. Initially he had hypocalcaemia but as rhabdomyolysis improved, his calcium levels started to rise to reach normal levels by day 13 post admission. By day 16, he started to gradually develop hypercalcemia. Initially, it was 2.73 mmol/L and in another 10 days it was 3.39 mmol/L and reached maximum of 3.90 mmo/L despite the intermittent dialysis sessions. PTH was supressed at 0.62 Pmol/L. Over that time, his renal functions and urine output were gradually improving.

The clinical impression was PTH independent hypercalcemia and the work up for that was initiated. CT chest, abdomen and pelvis did not reveal any suspicious masses, lytic bone lesions, or lymphadenopathies. His acid fast bacilli stain and culture were both negative. His chest imaging did not show any findings to suggest sarcoidosis. TSH was normal and random cortisol was 339.2 nmol/l with albumin 20g/L. HIV serology came back negative.

He received Calcitonin 500 IU BID for three days and Denosumab 120 mg SC in order to control the hypercalcemia along with, cautious intravenous hydration. Within one week after Denosumab therapy, serum corrected calcium decreased to 3.07 mmol/L. After another week, corrected calcium reached 2.53 mmol/L. When his urine output improved further and his calcium levels dropped, hemodialysis was discontinued. His calcium level later normalised to 2.49 mmol/L.

After ruling out the common differential of PTH independent hypercalcemia, and from the diuretic phase the patient went through with concomitant hypercalcemia following hypocalcaemia, it was concluded that the cause of hypercalcemia was rebound hypercalcemia following rhabdomyolysis recovery.

Conclusion: hypercalcemia can complicate the recovery phase of rhabdomyolysis. Careful monitoring of calcium levels and management are warranted.


[1] Mohsin N, Budruddin M, Pakkyara A. Calcium Kinetic in a Patient with Acute Renal Failure due to Rhabdomyolysis: A Case Report and Review of Literature. Oman Medical Journal. 2010;25:324–326.

<![CDATA[SAT-386 Inconsistent Bilateral Arm Serum PTH Testing in Recurrent Hyperparathyroidism in a Patient Status-Post Parathyroid Auto-Transplantation]]> Background: More than 95% of patients with primary hyperparathyroidism will be cured with the initial operation by an experienced surgeon. However, localization of hyperparathyroid recurrences, especially after extensive surgery becomes challenging. For patients with transplanted parathyroid glands into the forearm, there may be utility in bilateral arm serum PTH testing to help with localization.

Clinical Case:

A 65-year-old woman presented to the clinic with primary hyperparathyroidism in 2008. After a localization study, she had a partial parathyroidectomy but continued to have persistent biochemical hyperparathyroidism despite negative localization studies. She was then referred to another institution for further studies. Follow up Sestamibi scans were negative but 4D-CT scans assisted in localizing the presence of a superior parathyroid gland adenoma which was later removed in 2011. During this time, the left inferior parathyroid gland was auto-transplanted into the left forearm. Again, her calcium and PTH levels rose despite negative Sestamibi scans showing no abnormalities in post-operative beds or in the forearm. Review of previous labs revealed elevated PTH levels in the ranges of 80-110 pg/mL since 2012-2019. The patient’s most recent PTH was 2408 pg/mL. At that point, the decision was made to repeat the labs on the left and right forearms simultaneously and labs showed PTH levels of 1283 pg/mL and 118 pg/mL, respectively. Repeat Sestamibi scan following these labs demonstrated evidence of increased radiotracer uptake in the region of the prior transplanted parathyroid tissue with no neck uptake concerning for hyperparathyroidism due to auto-transplanted hyperplastic tissue.


This case demonstrates the utility of bilateral arm serum PTH testing in the evaluation of recurrent hyperparathyroidism in patient’s status-post parathyroid auto-transplantation.

<![CDATA[SAT-385 A Normal FGF23 Does Not Preclude Tumor Induced Osteomalacia (TIO)]]> BACKGROUND: The phosphaturic, bone-derived hormone FGF23, mediates bone loss in TIO. Tumor resection typically results in skeletal healing and reversal of biochemical defects.

Case: A 45-year-old Caucasian man with no past medical history presented with non-traumatic fractures of bilateral metatarsals. Over the subsequent 2 years, he sustained fragility stress fractures in bilateral femurs, eventually rendering him non-ambulatory; though he continued to work as a property manager in an office setting. History included 30 pack-years of smoking as well as osteochondrosarcoma in his mother. Labs showed a low phosphorus at 2.1 mg/dL [2.7–4.5], along with calcium 8.8 mg/dL [8.4–10.4], iPTH 48 pg/mL [12–88], and ALP of 155 [IU]/L [34–104]. 25-OH vitamin D and 1,25-(OH)2 vitamin D were 27 ng/mL [30–80] and 12 pg/mL [20–80], respectively. Free testosterone was 4.4 ng/mL [5–21] and LH 2.2 mIU/mL [3.0–10.0]. Other pituitary hormones and brain MRI were unremarkable.

Vitamin D3, calcitriol, phosphate and testosterone were prescribed. Testosterone was discontinued 6 months later, after diagnosis with DVT/PE. Incidental rib fractures on CXR prompted a 3-phase 99Tc-MDP bone scan, revealing multiple sites of uptake: ribs, scapulae, sternum, thoracolumbar spine, sacrum, bilateral ankles and feet. DXA revealed T-scores of -2.8 in the spine and -1.9 in the femoral neck.

Labs pointed to ongoing phosphate wasting, despite compliance with calcitriol 0.25 mcg, cholecalciferol 5000 IU and phosphorus 2250 mg in divided doses. Calculated TRP was 64% [>80%] and TmP/GFR 1.74 mg/dL [2.5–4.5], consistent with low phosphate reabsorption. Urine 24-hour calcium was 244.8 mg. Testing for causal mutations of hypophosphatemic rickets and osteogenesis imperfecta was negative. FGF23 was within the reference range at 138 RU/mL [LabCorp ELISA 44–215], interpreted as inappropriately normal given ongoing phosphate loss. This prompted a search for a suspected TIO locus.

Two years after presentation, 18F-FDG-PET exhibited a hypermetabolic focus at the left suprapatellar recess. Biopsy was consistent with a mesenchymal tumor and chromogenic in situ hybridization (Mayo Clinic) was positive for FGF23 mRNA. After surgical resection of the 1.7 cm tumor, serum FGF23 declined to <50 RU/mL and was 90 RU/mL 3 weeks later [Mayo <180 RU/mL]. Calcitriol and phosphorus supplementation were discontinued. One year post-operatively phosphorus was 3.6 mg/dL [2.5–5.0], with a normal calcium, iPTH and 25-OH vitamin D. Lumbar spine T score improved to -1.0 (+46.43%).

Conclusion: A high clinical index of suspicion is required for TIO in the setting of phosphaturic osteomalacia, particularly with a normal serum FGF23. Recently, similar microRNA profiles were noted in osteosarcomas and TIO1. This, along with our patient’s family history raises the question of a possible predisposition to skeletal neoplasms.

1. Green et al. Bone Reports, 2017.