title: Thyroidal effect of metformin treatment in patients with polycystic ovary syndrome.
abstract: 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.
  
  
  METHODS
  Aim of this study was to evaluate the effect of metformin treatment on the thyroid hormone profile in patients with PCOS.
  
  
  METHODS
  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 FT(4) 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.
authors.affiliation: Unit of Internal Medicine and Endocrinology, Fondazione Salvatore Maugeri IRCCS, ISPESL Laboratory for Endocrine Disruptors, University of Pavia, Pavia, Italy.
authors.forename: Mario
authors.initials: M
authors.lastname: Rotondi
authors.forename: Carlo
authors.initials: C
authors.lastname: Cappelli
authors.forename: Flavia
authors.initials: F
authors.lastname: Magri
authors.forename: Roberta
authors.initials: R
authors.lastname: Botta
authors.forename: Rosa
authors.initials: R
authors.lastname: Dionisio
authors.forename: Carmelo
authors.initials: C
authors.lastname: Iacobello
authors.forename: Pasquale
authors.initials: P
authors.lastname: De Cata
authors.forename: Rossella E
authors.initials: RE
authors.lastname: Nappi
authors.forename: Maurizio
authors.initials: M
authors.lastname: Castellano
authors.forename: Luca
authors.initials: L
authors.lastname: Chiovato
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D007004:Hypoglycemic Agents / Q000627:therapeutic use; D007037:Hypothyroidism / Q000150:complications / Q000188:drug therapy / Q000378:metabolism; D008687:Metformin / Q000627:therapeutic use*; D011085:Polycystic Ovary Syndrome / Q000150:complications / Q000188:drug therapy*; D013961:Thyroid Gland / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D013963:Thyroid Hormones / Q000097:blood / Q000378:metabolism*; D013972:Thyrotropin / Q000097:blood / Q000378:metabolism; D013974:Thyroxine / Q000097:blood / Q000378:metabolism; D013997:Time Factors; D016896:Treatment Outcome; D014284:Triiodothyronine / Q000097:blood / Q000378:metabolism; D055815:Young Adult
chemical_list: D007004:Hypoglycemic Agents; D013963:Thyroid Hormones; D014284:Triiodothyronine; D013972:Thyrotropin; D008687:Metformin; D013974:Thyroxine