Introduction: Subacute thyroiditis is a self-limited inflammation of the thyroid associated with recent upper respiratory tract viral infection. Graves’ disease has also been associated with viral illness.
Clinical Case:A 55-year-old female presented to the emergency department complaining of sore throat, cough, and shortness of breath. She also had fatigue, dyspnea on exertion, palpitations, and a family member who recently had bronchitis. She denied chest pain, weight changes, temperature intolerance, constipation, or diarrhea. She had never had similar symptoms before.
On initial evaluation, the patient was febrile at 101.2 °F, tachycardic at 156 beats per minute (bpm), and tachypneic at 33 breaths per minute. She was thin and her thyroid gland was tender upon palpation. She had eyelid lag, her skin was warm, and she was diaphoretic. Chest x-ray showed increased interstitial lung markings bilaterally. CBC showed anemia with hemoglobin of 9.7 g/dL (n<12 g/dL). Lactic acid was elevated to 2.00 mmol/L (n<1.9 mmol/L). D-dimer was 3020 ng/mL (n<230 ng/mL) and BNP was 961 pg/mL (n<100 pg/mL). An electrocardiogram showed sinus tachycardia at 140 bpm. Blood, sputum, and urine cultures were drawn, as were studies for viral respiratory pathogens. CT angiography of the chest and bilateral lower extremity venous ultrasound were ordered to rule out thromboembolism.
A point-of-care echocardiogram showed reduced ejection fraction of 20%. Thyroid function tests revealed TSH < 0.03 mIU/mL (range 0.5-5.0 mIU/L), free T4 of 4.5 ng/dL (n<2.15 ng/dL), and T3 251 ng/dL (n<200 ng/dL). Patient was started on an esmolol drip for heart rate control. CT angiogram of the chest was negative for thromboembolism but revealed a bilaterally enlarged thyroid gland with multiple small nodules. RNA for Respiratory Syncytial Virus (RSV) type A was detected by PCR. A thyroid ultrasound was done and revealed heterogenous echotexture with increased blast flow.
Thyroid antibody studies revealed thyrotropin receptor antibody of 26.5 IU/L (n<1.75 IU/L), thyroid-stimulating immunoglobulin 19.40 IU/L (n<0.55 IU/L), thyroglobulin antibody 235.6 IU/mL (n<0.9 IU/mL), and thyroid peroxidase antibody 11 IU/mL (range 0-34 IU/mL). Patient was started on methimazole 30 mg daily. A formal echocardiogram showed preserved ejection fraction of 50-55%. She was transitioned to oral propranolol. Patient’s shortness of breath and cough resolved, and she was discharged on methimazole 10 mg daily.
Conclusion:This case emphasizes the importance of measuring thyrotropin receptor antibodies in confirming Graves’ disease in a patient presenting with upper respiratory viral illness and supports the idea of viral-induced autoimmune thyroid disease.