Anemia metformin

Rosiglitazone - Reports of anemia were greater in patients treated with a combination of rosiglitazone and metformin compared with rosiglitazone monotherapy. Edema was reported with higher frequency in the rosiglitazone plus insulin combination trials. 

Metformin can cause reduced vitamin Bi2 absorption, reducing serum Bi2 concentrations and causing megaloblastic anemia (87), the prevalence of which was 9% in 600 patients with type 2 diabetes taking biguanides (phen-formin or metformin) for a mean of 12 years (88). In 353 patients with type 2 diabetes, treated with insulin, who took metformin for 16 weeks in a placebo-controlled study, metformin increased serum homocysteine concentrations by 4% and reduced serum folate by 7% and vitamin Bi2 by 14% (89). 

Megaloblastic anemia is rare with metformin, but vitamin Bi2 concentrations can be reduced by metformin and phenformin (92) because of reduced absorption, and pre-existing deficiency can be exacerbated (64). 

Fujita H, Narita T, Yoshioka N, Hosoba M, Ito S. A case of megaloblastic anemia due to vitamin B12 deficiency precipitated in a totally gastrectomized type II diabetic patient following the introduction of metformin therapy. Endocr J 2003 50 483 1. 

Meir A, Kleinman Y, Rund D, Da as N. Metformin-induced hemolytic anemia in a patient with glucose-6-phosphate dehydrogenase deficiency. Diabetes Care 2003 26(3) 956-7. 

Contraindications for metformin include renal insufficiency, liver disease, alcehel abuse, cardiac insufficiency, metabolic acidosis or any hypoxia-related conditien. An additional consideration is that chronic metformin therapy can decrease oral absorption and subsequent serum concentrations of cyanocobalamin (vitamin B12) nevertheless, this effect, which is seen in approximately one in four patients, dees not appear to result in anemia. 

Hematologic Metformin-induced hemolytic anemia is rare and generally not fatal the time to onset of symptoms after starting metformin is about 10 days. A fatal case has been reported [41 ]. 

Packer CD, Homick TR, Augustine SA. Fatal haemolytic anemia associated with metformin a case report. J Med Case Rep 2008 2 300. 

Responsibilities for management of chronic and preoperative medication need to be clearly defined and communicated between all involved caregivers. Timely prescription (e.g. treatment of preoperative anemia), reliable continuation (e.g. beta-blockers, aspirin, statins) [2], timely discontinuation (e.g. metformin, platelet inhibitors, new oral anticoagulants), and effective bridging (insulin, unfractionated heparin) of preoperative medications increase patient safety by reducing risks of myocardial ischemia, bleeding and transfusion, and help to avoid case cancellations. 

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