Renal failure in a patient with profound hypothyroidism

A young man presented with a 4 week history of easy fatiguability, loss of appetite, and puffiness of face and lower extremities, and was found to have a serum creatinine of 2.0 mg/dL with a normal urinalysis, negative serology for autoimmune disorders, but moderately elevated serum creatine phosphokinase (CPK). A renal biopsy revealed normal glomeruli with no evidence of any pathology except for the presence of brownish pigmented casts in some of the proximal and distal tubules suggestive of myoglobinuria. He was subsequently found to be profoundly hypothyroid with a thyroid stimulating hormone (TSH) level of >100 mu U/mL. He had marked symptomatic improvement after institution of thyroid replacement therapy with a decline in serum creatinine to 1.3 mg/dL at 6 weeks follow up.