Version May 2024
Refer to a separate algorithm for diagnosis of vitamin B12 deficiency, including use of the MMA level in people with borderline vitamin B12 levels. If not known, the cause of vitamin B12 deficiency must be determined as it has implications for the route of administration, duration of therapy, and other testing or treatments that may be indicated. Intranasal, transdermal, and oral "timed release" formulations of vitamin B12 are not recommended, and vitamin B12 is not given intravenously.
Refer to UpToDate for pediatric dosing.
Vitamin B12 administration should lead to a reticulocytosis within several days, improvement in the hemoglobin in 1 to 2 weeks, and normalization of the hemoglobin and MCV within 4 to 8 weeks. Neurologic symptoms may resolve or stabilize without complete resolution. Refer to UpToDate for details.IM: intramuscular; SL: sublingual; CBC: complete blood count; MMA: methylmalonic acid (increased in vitamin B12 deficiency); MCV: mean corpuscular volume.
* Malabsorption is classically due to pernicious anemia (PA; vitamin B12 deficiency caused by autoantibodies to intrinsic factor or gastric parietal cells). Other causes may include bariatric, gastric, or small intestinal surgery. Some experts will use oral vitamin B12 as initial therapy for individuals with malabsorption if they do not have severe anemia or neurologic complications and if adherence was assured. Refer to UpToDate for diagnostic testing for PA and other evaluations.
¶ Dose and frequency depend on the level of concern and the costs and burdens of therapy, with shared decision making. For severe deficiency, daily dosing for the first week can be considered. If a dose increase is needed due to insufficient response, it is reasonable to increase the dosing frequency (eg, 1000 mcg IM every 2 weeks) and/or increase the dose (eg, 2000 mcg orally instead of 1000 mcg). Lower doses are used for children (refer to UpToDate for details).آیا می خواهید مدیلیب را به صفحه اصلی خود اضافه کنید؟
