SERUM T3 AND T4 LEVELS IN PATIENTS WITH ANOREXIA NERVOSA SHOWING TRANSIENT HYPERTHYROIDISM DURING WEIGHT GAIN

Abstract

Serum thyroxine (T4) and triiodothyronine (T3) levels were measured in a group of thirty‐three patients with anorexia nervosa (AN) and compared with twenty‐five control women presenting with hirsutism and twenty‐one patients with primary myxoedema. T3 levels in the AN patients were significantly lower than in the control subjects and in the patients with myxoedema while T4 levels were significantly higher than in the patients with hypothyroidism but significantly lower than in the control group. Seventeen anorexia patients had further T3 and T4 levels measured following an arbitrary 25% weight gain and both levels had increased significantly. For individual patients, the absolute rise in T3 levels was significantly correlated with the rate of weight gain. Thirteen patients had serial T3 and T4 levels measured during their periods of weight gain. Eight of these subjects showed a gradual rise in T3 levels from subnormal or low normal levels to values in the upper normal range. Four subjects showed a distinct and self limiting overshoot of T3 levels and, associated with this, the patients had clinical features of mild hyperthyroidism.