Thyroid functions in lithium-treated psychiatric patients: a cross-sectional study.

In the present cross-sectional study, thyroid functions (viz. thyroid radioiodine uptake [RAIU] and serum T3, T4, and thyroid-stimulating hormone [TSH]) were evaluated in 24 healthy controls and 132 outdoor affective disorder patients. Eleven of these patients were to receive lithium (Li) and the remaining 121 patients were at different stages of Li treatment ranging from 0.7 to 240 mo. RAIU was found to increase significantly throughout the Li therapy and was associated with the corresponding rise in TSH levels. In totality, Li treatment induced subclinical hypothyroidism in 51/132 (39%) of patients. However, 8/51 patients who belonged to known iodine-deficient belt had abnormally high TSH (range 15.2-76.0 microIU/mL), low T4 (5.3+/-2.5 microg/dL), and normal T3 and at least 4 of these 8 patients were clinically hypothyroid. T4 levels declined significantly (p < 0.05) with Li treatment ranging from 61 to 240 mo as compared to the corresponding values in the pre-Li group. The T3/T4 ratio was found to be significantly higher with Li treatment ranging from 0.7 to 6 mo in comparison with the pre-Li group and this value returned to base levels after long-term Li therapy. High T3 and T4 were observed in 13% and 12% of the patients, respectively, as compared to the corresponding control values.