Thyroid hormone resistance in a 35-year old man with recurrent goitre

Without firm diagnosis a 16-year old boy was submitted to subtotal thyroidectomy because of a diffuse goitre and emotional instability. No definite improvement was obtained in the alleged toxic symptoms and the goitre recurred. During subsequent years increased serum concentrations of thyroid hormones have repeatedly been observed in the absence of clear-cut hyperthyroid symptoms. Judging from clinical examination and a normal basal metabolic rate the patient, now 35 years old, was euthyroid at the present study. Basal serum-TSH concentration was normal to slightly elevated; it was definitely abnormal in relation to the high serum concentration of free T4. Serum T4, T3 and rT3 concentrations were also abnormally high in the face of normal levels of TBG and prealbumin. Agarose gel electrophoresis revealed normal binding pattern for T4. After 200 micrograms of TRH intravenously there was an abnormally high rise of serum TSH. Concentrations of prolactin and glycopeptide-hormone alpha subunit as well as the pituitary-gonadal and adrenocortical functions were normal. Sella turcica was seemingly normal. During oral administration of T3, 160 micrograms daily for 5 days, the circulating T4, free T4 and rT3 concentrations decreased and the response to TRH was suppressed to that found in normal, untreated individuals. However, no clinical response to the drug was seen and the metabolic rate was unchanged. The patient had poor performance at school but acceptable performance at routine manual work. He had defective colour vision, a refractory anomaly, neurogenic auditory damage but no skeletal abnormalities. Laboratory investigation revealed features characteristic of partial thyroid hormone resistance in the pituitary and the peripheral tissues.