Cortisol secretion and metabolism in anorexia nervosa.

We studied cortisol secretion and metabolism in 10 women with anorexia nervosa. The 24-hour mean plasma cortisol concentration was 8.9 mug per deciliter (controls, 4.9) (P less than 0.01). Secretory patterns showed normal circadian rhythms. Cortisol half-life was prolonged from 60 to 78 minutes (P less than 0.01), and metabolic clearance rate was decreased from 359 to 177 liters per day (P less than 0.001). Cortisol production was normal (19.4 mg per day). Urinary cortisol was slightly elevated in two of five patients. These findings, as well as the increased tetrahydrocortisol/tetrahydrocortisone ratio (1.2 vs 0.65, P less than 0.01), also appear in hypothyroid patients. Thyroid-function studies showed normal total and free thyroxine and thyrotropin, but low plasma tri-iodothyronine levels (52.7+/-13.2 vs. 137.8+/-24.1 ng per deciliter in the controls, P less than 0.001). In five additional patients with anorexia nervosa studied before and after short-term tri-iodothyronine administration, metabolic abnormalities decreased as plasma tri-iodothyronine levels rose to or above normal.