Subclinical hypothyroidism in lithium-treated psychiatric patients in Tehran, Islamic Republic of Iran.

We investigated thyroid function in 46 (20 female & 26 male) psychiatric outpatients on lithium treatment by assessing triiodothyronine, thyroxine and thyroid stimulating hormone (TSH) levels. The presence of thyroid antibodies (anti-thyroid peroxidase and anti-thyroglobulin) was also assessed. Out of the 46 patients, 8 (17%) displayed overt hypothyroidism. Of the remaining patients, subclinical hypothyroidism was found in 16 patients (35%) and euthyroidism in 22 (48%). Thyroid antibodies were present in 6 patients in the euthyroid group and 5 patients in the hypothyroid group. The Pearsor product-moment correlation results indicated positive association between TSH level and duration of lithium use and age of the patients with subclinical hypothyroidism. Duration of lithium use and age could be a reasonable indicator for screening asymptomatic patients for subclinical hypothyroidism after starting lithium treatment.