A 50 year old female initially presented with progressive weight gain and mood swings. She had normal 24 h urine cortisol, but an elevated midnight serum cortisol. She underwent transphenoidal surgery for a presumed ACTH-dependent Cushing’s disease. Pathology was not supportive of a pituitary adenoma, showing adenohypophyseal tissue with focal expansion of the acini. The surgery was complicated by hypothyroidism and growth hormone deficiency. She was able to weaned off of the steroids after a few months. She had recurrence of her initial symptoms, she was found to have elevated late evening and morning cortisol levels. She underwent a bilateral adrenelactomy for “recurrence of the cyclical Cushing’s symptoms.” She was started on HC replacement; 10 mg AM and 2.5 mg PM, florinef 0.05 mg daily. She slowly lowered the hydrocortisone dose, and as a result lost 120 lbs.
Three years later she presented with fatigued and gaining weight, by that time she was on Hydrocortisone 3.75 mg AM, 1.25 mg evening, and fludrocortisone 0.1 mg/day. ACTH was 355 (6–48 pg/ml), serum cortisol 10 (8–19 ug/dl) on Hydrocortisone and < 1.0 ug/dl off cortisone. The 24 h urine free cortisol < 1.0 (10–24 ug/34h), and 17 OH- corticosteroids < 4.8(4–14 mg/dl). A possible adrenal remnant was seen on abdominal CT, surgically removed of the lesion showed a lipoma.
She was referred to Neurosurgery for a second pituitary surgery for the concern Cushing’s recurrence. A pituitary MRI revealed a small potential microadenoma. The small dose of hydrocortisone was held for 48 h and an 8 AM test dose: Serum cortisol < 1.20 mcg/dl (3–18), ACTH 1,077 pg/ml (5–72), 24 h urine cortisol < 1.5 mcg/24h (3.5–45), 24 h urine cortisone 10 mcg/24h (17–129), and two midnight salivary cortisol were 128 and 265 ng/dl (< 100 ng/dl). There was a concern raised by the laboratory for a contaminated salivary sample, as the salivary cortisol to cortisone ratio was concerning for contamination with exogenous steroid (1)
Work up for Cushing’s syndrome can be very confusing and frustrating at times for the patient and their physicians. Doing a meticulous work up is necessary to reach an accurate conclusion. Misdiagnosing Cushing’s can lead to a cascade of mistreatment with serious consequences. The case presented highlights the challenges encountered in taking care of such patients. It is necessary to understand the pre-testing probability to reach a precise conclusion. Factitious disorder or sample contamination can be yet another challenge in the differential diagnosis of Cushing’s work up.