Hyperthyroxinemia in patients with acute psychiatric disorders

Thyroid function tests were measured in 645 patients admitted to an acute psychiatric disorders unit. Thirty-three percent had elevated serum thyroxine (T 4), and 18 percent had an elevated free T 4 index (FTI). Serum triiodothyronine (T 3) was low, normal, or minimally elevated in 77 patients, with a high initial free T 4 index. Twenty-two patients with an initial elevation of their free T 4 index were serially followed (study group). Serum T 4, free T 4 index, and free T 4 fell in every patient: serum T 4 from 13.95 ± 1.93 μg/dl (mean ± standard deviation: SD) to 9.33 ± 2.4 μg/dl (p < 0.001); free T 4 index, from 6.15 ± 0.83 to 3.79 ± 1.1 (p < 0.001); free T 4, from 2.43 ± 0.65 ng/dl to 1.38 ± 0.35 ng/dl (p < 0.001). Serum T 3 was initially normal or low, and then fell in 17 patients, and rose in five. Serial testing of thyrotropin-releasing hormone (TRH) demonstrated both flat and normal responses in patients with a variety of psychiatric diagnoses and at varying stages of thyroid disease activity.