(click the title above to get to the paper)
Mario Rotondi et al.
Clin Endocrinol. 2011;75(3):378–381
Objective
Metformin is widely used for the treatment of type 2 diabetes. Growing evidence supports the beneficial effects of metformin also in patients with polycystic ovary syndrome (PCOS). It was recently reported that metformin has a TSH-lowering effect in hypothyroid patients with diabetes being treated with metformin.
Design
Aim of this study was to evaluate the effect of metformin treatment on the thyroid hormone profile in patients with PCOS.
Patients and measurements
Thirty-three patients with PCOS were specifically selected for being either treated with
levothyroxine for a previous diagnosis of hypothyroidism (n = 7), untreated subclinically hypothyroid (n = 2) or euthyroid without levothyroxine treatment (n = 24) before the starting of metformin. The serum levels of TSH and FT4 were measured before and after a 4-month period of metformin therapy.
Results
Thyroid function parameters did not change after starting metformin therapy in euthyroid patients with PCOS. In the 9 hypothyroid patients with PCOS, the basal median serum levels of TSH (3!2 mIU/l, range = 0!4–7!1 mIU/l) significantly (P < 0!05) decreased after a 4-month course of metformin treatment (1!7 mIU/l, range = 0!5–5!2 mIU/l).
No significant change in the serum levels of FT4 was observed in these patients. The TSH-lowering effect of metformin was not related to the administered dose of the drug, which was similar in euthyroid as compared with hypothyroid patients with PCOS (1406 ± 589 vs 1322 ± 402 mg/day, respectively; NS).
Conclusions
These results indicate that metformin treatment has a TSH-lowering effect in hypothyroid patients with PCOS, both treated with l-thyroxine and untreated.
