Ultrasonically determined thyroid volume and thyroid functions in lithium‐naïve and lithium‐treated patients with bipolar disorder: a cross‐sectional and longitudinal study

Abstract

This study investigated thyroid volume, hormone levels and antibodies in long-term lithium-treated and lithium-naïve bipolar patients, some of whom underwent prospective follow-up evaluations. Fourteen lithium-naïve patients, 13 long-term lithium-treated patients diagnosed with bipolar disorder and 12 healthy controls were included. Seven lithium-naïve patients were followed-up during their lithium receiving period (range 6-9 months). Thyroid volume and serum levels of thyroid hormones and antibodies were measured once in the long-term lithium-treated patients and controls, and twice in the lithium-naïve patients, i.e. before and after lithium treatment. Mean thyroid volumes in the lithium-naïve patients were significantly higher than those in the controls. Long-term lithium-treated patients had significantly higher total thyroid volume than the lithium-naïve patients and the controls. Total thyroid volume in the patients after the lithium treatment was significantly higher than that before. Serum free thyroxine (fT4) levels in the long-term lithium-treated patients were lower than those in the lithium-naïve patients and the controls. In the lithium-naïve patients, after lithium treatment, free triiodothyronine (fT3) levels were lower, and thyroid stimulating hormone (TSH) levels were higher compared to those before lithium treatment. The results suggest that thyroid enlargement and some alterations in thyroid hormones in bipolar patients may present even before lithium treatment and increase further with lithium treatment.