title: Metformin lowers serum cobalamin without changing other markers of cobalamin status: a study on women with polycystic ovary syndrome.
abstract: Treatment with the anti-diabetic drug metformin is followed by a decline in plasma cobalamin, but it is unsettled whether this denotes an impaired cobalamin status. This study has explored changes in the markers of cobalamin status in women with Polycystic Ovary Syndrome treated with metformin (1.5-2.5 g per day) (n = 29) or placebo (n = 23) for six months. Serum samples were collected before and after two, four, and six months of treatment. We found serum cobalamin to decline and reach significant lower levels after six months of treatment (p = 0.003). Despite the decline in serum cobalamin, we observed no reductions in the physiological active part of cobalamin bound to transcobalamin (holotranscobalamin), or increase in the metabolic marker of cobalamin status, methylmalonic acid. Instead, the non-functional part of circulating cobalamin bound to haptocorrin declined (p = 0.0009). Our results have two implications: The data questions whether metformin treatment induces an impaired cobalamin status in PCOS patients, and further suggests that serum cobalamin is a futile marker for judging cobalamin status in metformin-treated patients.
authors.affiliation: Department of Clinical Biochemistry, Aarhus University Hospital, Norrebrogade 44, 8000 Aarhus C, Brendstrupgaardsvej 100, 8200 Aarhus N, Denmark. evagreibe@gmail.com
authors.forename: Eva
authors.initials: E
authors.lastname: Greibe
authors.forename: Birgitta
authors.initials: B
authors.lastname: Trolle
authors.forename: Mustafa V
authors.initials: MV
authors.lastname: Bor
authors.forename: Finn F
authors.initials: FF
authors.lastname: Lauszus
authors.forename: Ebba
authors.initials: E
authors.lastname: Nexo
mesh_terms: D000293:Adolescent; D000328:Adult; D015415:Biomarkers / Q000097:blood*; D015992:Body Mass Index; D015331:Cohort Studies; D018592:Cross-Over Studies; D005260:Female; D006801:Humans; D007004:Hypoglycemic Agents / Q000008:administration & dosage; D008687:Metformin / Q000008:administration & dosage*; D008875:Middle Aged; D011085:Polycystic Ovary Syndrome / Q000097:blood* / Q000188:drug therapy*; D014805:Vitamin B 12 / Q000097:blood*; D055815:Young Adult
chemical_list: D015415:Biomarkers; D007004:Hypoglycemic Agents; D008687:Metformin; D014805:Vitamin B 12