Iatrogenic Hyperthyroidism

Abstract

A 45-year-old salesman was referred for consultation regarding treatment of hypothyroidism. He had been diagnosed with hypothyroidism by his internist about 20 years earlier, in 1972. Old records were not available, but he recalled that some tests were done and he was started on Thyrolar 2. Several years later, the thyroid dosage was increased to Thyrolar 3, roughly equivalent to 0.3 mg of thyroxine (T₄). Tests were done by his doctor approx 1 year prior to this visit and he was told he was taking too much thyroid. He was switched to T₄ and the dosage was slowly decreased to his current level of 0.15 mg daily. He would note generalized aching every time the dose was decreased. On the higher doses, the aching would improve after 2 or 3 months. However, after the last dose reduction, the aching persisted, and he also noted fatigue. A recent thyroid-stimulating hormone (TSH) on 0.15 mg of T₄ was low-normal at 1.03. Physical examination was completely normal.