The prevalence of thyroid dysfunction in mentally handicapped in-patients.

A survey was made of the thyroid function of 402 mentally handicapped patients in a long-stay hospital and its satellite units. The prevalence of hypothyroidism in a 2-year period was 25/402 (6.2%), and 17/364 (4.7%) when people with Down's syndrome were excluded. Hyperthyroidism was found in 3/402 (0.7%). These results include 16 patients with hypothyroidism, and two with hyperthyroidism, who were newly detected during the surgery. With diagnosis, treatment was started. This occurrence of thyroid disorders is higher than in both the general population in the community and also in other psychiatric in-patients. Biochemical investigation is essential as the disorders are difficult to detect clinically, and untreated the patients are liable to the complications of hypothyroidism and hyperthyroidism.