Thyroid function screening in psychiatric patients.

Abnormalities in levels of total thyroxine and thyroxine binding capacity were common in a group of 480 newly admitted psychiatric patients. The estimated free thyroxine (EFT4) level was elevated in 43 patients (9%). In 27 of these patients, the level of EFT4 became spontaneously normal, usually within a two-week period (acute "stress hyperthyroidism"). The level of EFT4 was decreased in 42 patients (9%). In 16 of these patients, the level became spontaneously normal; the etiology of this apparent acute hypolhyroidism is unclear. The yield of new cases of primary hyperthyroidism and hypothyroidism was low, but a presumptive diagnosis of secondary hypothyroidism was made in eight patients. In addition, nine patients with known thyroid disease were taking inadequate or excessive replacement therapy. Thyroid function screening tests are of value in psychiatric patients.