title: The effect of metformin on prolactin levels in patients with drug-induced hyperprolactinemia.
abstract: BACKGROUND
  In bromocriptine-treated hyperprolactinemic patients with impaired glucose tolerance, metformin was found to reduce plasma levels of prolactin. No previous study has investigated its impact on plasma prolactin in patients with drug-induced hyperprolactinemia.
  
  
  METHODS
  The study included 20 women with antipsychotic-induced hyperprolactinemia and 12 normoprolactinemic women, who, because of coexisting glucose metabolism abnormalities, were treated for 6months with metformin. Hyperprolactinemic patients with prediabetes received moderate doses of metformin (1.7g daily), while hyperprolactinemic and normoprolactinemic patients with type 2 diabetes were treated with high-dose metformin (2.55-3g daily). Fasting plasma glucose levels, the homeostatic model assessment 1 of insulin resistance ratio (HOMA1-IR), glycated hemoglobin, as well as plasma levels of prolactin, thyrotropin, adrenocorticotropic hormone and insulin-like growth factor-1 were assessed at baseline and after 6months of treatment.
  
  
  RESULTS
  Despite reducing plasma glucose, HOMA1-IR, and glycated hemoglobin in all treatment groups, metformin decreased prolactin levels only if given at high doses to patients with elevated prolactin levels. No changes in thyrotropin, adrenocorticotropic hormone, and insulin-like growth factor-1 were observed in any treatment groups.
  
  
  CONCLUSIONS
  The obtained results suggest that the effect of metformin on plasma prolactin depends on its dose and is observed only in patients with elevated levels of this hormone.
authors: Department of Internal Medicine and Clinical Pharmacology, Medical University of Silesia, Medyków 18, 40-752 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, Medyków 18, 40-752 Katowice, Poland.
authors: Karolina
authors: K
authors: Kowalcze
authors: Department of Internal Medicine and Clinical Pharmacology, Medical University of Silesia, Medyków 18, 40-752 Katowice, Poland.
authors: Witold
authors: W
authors: Szkrobka
authors: Department of Internal Medicine and Clinical Pharmacology, Medical University of Silesia, Medyków 18, 40-752 Katowice, Poland.
authors: Boguslaw
authors: B
authors: Okopien
mesh_terms: D000328:Adult; D014150:Antipsychotic Agents / Q000009:adverse effects; D001786:Blood Glucose / Q000187:drug effects; D003924:Diabetes Mellitus, Type 2 / Q000188:drug therapy*; D005260:Female; D006801:Humans; D006966:Hyperprolactinemia / Q000139:chemically induced / Q000188:drug therapy*; D007004:Hypoglycemic Agents / Q000008:administration & dosage*; D008687:Metformin / Q000008:administration & dosage*; D008875:Middle Aged; D011044:Poland; D011388:Prolactin / Q000097:blood*; D013972:Thyrotropin / Q000097:blood
chemical_list: D014150:Antipsychotic Agents; D001786:Blood Glucose; D007004:Hypoglycemic Agents; D011388:Prolactin; D013972:Thyrotropin; D008687:Metformin
keywords: Diabetes mellitus; Drugs; Hyperprolactinemia; Metformin