Thyroid function test abnormalities in newly admitted psychiatric patientsresiding in an iodine-deficient area: patterns and clinical significance

Objective: The prevalence of abnormal in-vitro thyroid function tests in ps ychiatric in-patients may be as high as 24%. Thus far, however, there is on ly limited data addressing the underlying causes of these abnormal test res ults, i.e. how often they can be attributed to genuine thyroid disease. Method: We conducted an observational study of all in-patients admitted to our institution during I calendar year running analyses of total thyroxin ( T4), free thyroxin index (FTI) and thyroid-stimulating hormone (TSH). Patie nts with abnormal test results were classified according to an algorithm wh ich had been established previously. Results: In 243 of 880 patients with hm;itro thyroid function analysis, at least one concentration of either T4, FT1 or TSH was found to be outside th e reference range. Work-tip according to the algorithm was completed in 848 patients; alterations were classified as representing thyroid dysfunction in 100 (41% of patients with abnormal test results), nonspecific findings i n 92 (38%), influence of ingested drugs in 18 (7%) and of severe physical d isease in 1 (0.4%). As measures of T4 and/or FTI provided no essential info rmation in 854 patients (97% of tested), we found that in most cases the de termination of TSH alone was sufficient for demonstrating normal thyroid fu nction. Conclusion: In 27.6% of newly admitted patients living in an iodine-deficie nt area, at least one abnormal result in either T4, FTI or TSH values was f ound. Genuine thyroid disease was found in slightly less than half the pati ents with an abnormal value.