Hypothyroid-like alterations in testosterone metabolism in anorexia nervosa.

The metabolism of 14C-testosterone was studied in 8 severely underweight young women with anorexia nervosa. The urinary androsterone/etiocholanolone (A/E) ratio was uniformly low, in a range characteristic of hypothyroidism; the patients also showed low plasma concentrations of triiodothyronine (T3). Clinical remission as manifested by weight gain was accompanied by concomitant increases of the A/E ratio and the plasma T3 concentration to or toward normal. The administration of T3 also resulted in a shift of the A/E ratio toward normal. These data demonstrate that the low plasma T3 concentrations in patients with anorexia nervosa may be related to the development of one of the characteristic biochemical abnormalities found in clinical hypothyroidism, namely a decreased A/E ratio. These data suggest that the "low T3 syndrome" may be associated with biochemical hypothyroidism.