Thyroid disease and mental illness: a study of thyroid disease in psychiatric admissions.

The notes of 1007 consecutive admissions to a District General Hospital adult psychiatry unit were examined retrospectively to establish the role of the thyroid disease detected in routine management. Thyroid function tests were performed on 300 admissions, leaving 707 untested. Ten had abnormal results (3.3% of admissions tested), accounted for by nine patients with affective disorder. Two of the nine settled spontaneously, but seven cases (2.3%) had sustained abnormality. Five of the seven had a known history of thyroid disease, leaving two new findings of hypothyroidism who presented with no clinical signs other than their mental illness (0.7% of admissions tested). In five cases, which included the two new findings, the thyroid disease had been judged to precipitate the mental illness. All cases except one transitory abnormality occurred in females. When the results of this and other surveys are compared with the figures for thyroid disease in the general population, the value of screening psychiatric patients seems questionable. However, diagnosis is important in a few cases where thyroid disease apparently contributes to the mental illness. For psychiatric patients aged up to 65, elimination of unnecessary thyroid function tests without sacrificing detection may be possible by restricting use to female patients with affective disorder, patients with a past or family history of thyroid disease or with presenile dementia. Abnormal results obtained during the acute phase of the illness may be transitory and require confirmation.