title: Sex-dependent effect of metformin on hypothalamic-pituitary-thyroid axis activity in patients with subclinical hypothyroidism.
abstract: BACKGROUND
  Metformin was found to reduce elevated serum thyrotropin levels. No previous study has compared the effect of this drug on serum levels of thyrotropin and thyroid hormones between men and women.
  
  
  METHODS
  The study included 23 women and 12 men with subclinical hypothyroidism, who because of coexisting diabetes or impaired fasting glucose were treated with metformin (1.7-3.0g daily). Fasting plasma glucose levels, the homeostatic model assessment 1 of insulin resistance ratio (HOMA1-IR), glycated hemoglobin, serum levels of thyrotropin, free and total thyroid hormones and prolactin, as well as thyroid peroxidase and thyroglobulin antibodies were assessed at baseline and after 4 months of metformin treatment.
  
  
  RESULTS
  Baseline serum levels of thyrotropin, free thyroxine and free triiodothyronine, as well as a percentage of patients with positive thyroid peroxidase and thyroglobulin antibodies were comparable in both sexes. Metformin treatment reduced plasma glucose and insulin resistance, irrespective of the gender. However, only in women, metformin decreased serum thyrotropin levels. Neither in men nor in women, metformin affected serum levels of thyroid hormone and prolactin, as well as in the subgroups of patients with thyroiditis thyroid antibody titers.
  
  
  CONCLUSIONS
  The obtained results suggest that sex may determine the effect of metformin on hypothalamic-pituitary-thyroid axis activity.
authors: Department of Internal Medicine and Clinical Pharmacology, Medical University of Silesia, Katowice, Poland. Electronic address: r.krysiak@interia.pl.
authors: Robert
authors: R
authors: Krysiak
authors: Department of Internal Medicine and Clinical Pharmacology, Medical University of Silesia, Katowice, Poland.
authors: Witold
authors: W
authors: Szkróbka
authors: Department of Internal Medicine and Clinical Pharmacology, Medical University of Silesia, Katowice, Poland.
authors: Bogusław
authors: B
authors: Okopień
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D007004:Hypoglycemic Agents / Q000494:pharmacology / Q000627:therapeutic use; D007030:Hypothalamo-Hypophyseal System / Q000187:drug effects* / Q000378:metabolism; D007037:Hypothyroidism / Q000188:drug therapy* / Q000378:metabolism; D008297:Male; D008687:Metformin / Q000494:pharmacology* / Q000627:therapeutic use; D008875:Middle Aged; D010913:Pituitary-Adrenal System / Q000187:drug effects* / Q000378:metabolism; D012727:Sex Characteristics; D013961:Thyroid Gland / Q000187:drug effects* / Q000378:metabolism; D013972:Thyrotropin / Q000097:blood; D013974:Thyroxine / Q000097:blood; D014284:Triiodothyronine / Q000097:blood
chemical_list: D007004:Hypoglycemic Agents; D014284:Triiodothyronine; D013972:Thyrotropin; D008687:Metformin; D013974:Thyroxine
keywords: Hypothalamic-pituitary-thyroid axis; Insulin resistance; Metformin; Sex