Homocysteine, folate, and cobalamin levels in hyperthyroid women before and after treatment.

INTRODUCTION Hyperhomocysteinaemia is an independent risk factor for premature atherosclerotic vascular disease and venous thrombosis. Hypothyroidism is associated with mild hyperhomocysteinaemia. The aim of the present study was to assess plasma total homocysteine (tHcy) and its determinants (folate, cobalamin) in hyperthyroid patients before and after treatment. MATERIAL AND METHODS Thirty hyperthyroid and thirty healthy premenopausal women were studied. The hyperthyroid patients were investigated in the untreated state and again after restoration of euthyroidism. The levels of homocysteine, folate, cobalamin, and thyroid stimulating hormone (TSH), free thyroxine (fT(4)), free triiodothyronine (fT(3)), and renal function were measured before and after treatment. RESULTS In hyperthyroidism, tHcy was lower than in the control group. The serum level of folate was higher and serum cobalamin was lower in the hyperthyroid state. Following antithyroid drug therapy, tHcy significantly increased and folate decreased. The level of cobalamin remained unchanged. Univariate analysis in the hyperthyroid group indicated that tHcy significantly negatively correlated only with fT(3). CONCLUSIONS Lower homocysteine levels in hyperthyroid state can be explained by the influence of thyroid hormone. High level of folate is only partially responsible for these changes.