Routine screening of thyroid function in patients hospitalized for major depression or dysthymia?

Our objective was to examine the clinical practice of testing thyroid function in a mixed community and referral psychiatry inpatient unit. We evaluated (1) the frequency of ordering screening, (2) the type of test, and (3) the incidence of thyroid function abnormality among those tested. We reviewed thyroid function tests obtained on 277 consecutive first time adult admissions to the psychiatric wards at Walter Reed Army Medical Center, from 1992 through 1993, who met the DSM-III R diagnostic criteria for major depression or dysthymia. Of the 277 subjects, 260 (94%) had thyroid function tests performed which included evaluation of thyroid stimulating hormone (TSH). Seventeen patients (6.5%) had a TSH outside the normal range. Of these, there were two cases (0.4%) suggestive of hyperthyroidism and no overt cases of hypothyroidism. Eight patients had subclinical hypothyroidism (elevated TSH, normal T4). Although screening thyroid tests are often routine for depressed inpatients, our data suggest that thyroid screening may add little to diagnostic evaluation. Overt thyroid disease is rare among depressed inpatients.