Items in AFP with MESH term: Vitamin B 12 Deficiency
Vitamin B12 Deficiency - Article
ABSTRACT: Vitamin B12 (cobalamin) deficiency is a common cause of macrocytic anemia and has been implicated in a spectrum of neuropsychiatric disorders. The role of B12 deficiency in hyperhomocysteinemia and the promotion of atherosclerosis is only now being explored. Diagnosis of vitamin B12 deficiency is typically based on measurement of serum vitamin B12 levels; however, about 50 percent of patients with subclinical disease have normal B12 levels. A more sensitive method of screening for vitamin B12 deficiency is measurement of serum methylmalonic acid and homocysteine levels, which are increased early in vitamin B12 deficiency. Use of the Schilling test for detection of pernicious anemia has been supplanted for the most part by serologic testing for parietal cell and intrinsic factor antibodies. Contrary to prevailing medical practice, studies show that supplementation with oral vitamin B12 is a safe and effective treatment for the B12 deficiency state. Even when intrinsic factor is not present to aid in the absorption of vitamin B12 (pernicious anemia) or in other diseases that affect the usual absorption sites in the terminal ileum, oral therapy remains effective.
Evaluation of Macrocytosis - Article
ABSTRACT: Macrocytosis, generally defined as a mean corpuscular volume greater than 100 fL, is frequently encountered when a complete blood count is performed. The most common etiologies are alcoholism, vitamin B12 and folate deficiencies, and medications. History and physical examination, vitamin B12 level, reticulocyte count, and a peripheral smear are helpful in delineating the underlying cause of macrocytosis. When the peripheral smear indicates megaloblastic anemia (demonstrated by macro-ovalocytes and hyper-segmented neutrophils), vitamin B12 or folate deficiency is the most likely cause. When the peripheral smear is non-megaloblastic, the reticulocyte count helps differentiate between drug or alcohol toxicity and hemolysis or hemorrhage. Of other possible etiologies, hypothyroidism, liver disease, and primary bone marrow dysplasias (including myelodysplasia and myeloproliferative disorders) are some of the more common causes.
Is Oral Vitamin B12 as Effective as Intramuscular Injection? - Cochrane for Clinicians
ABSTRACT: Anemia is a prevalent condition with a variety of underlying causes. Once the etiology has been established, many forms of anemia can be easily managed by the family physician. Iron deficiency, the most common form of anemia, may be treated orally or, rarely, parenterally. Vitamin B12 deficiency has traditionally been treated with intramuscular injections, although oral and intranasal preparations are also available. The treatment of folate deficiency is straightforward, relying on oral supplements. Folic acid supplementation is also recommended for women of child-bearing age to reduce their risk of neural tube defects. Current research focuses on folate's role in reducing the risk of premature cardiovascular disease.
Anemia in the Elderly - Article
ABSTRACT: Anemia should not be accepted as an inevitable consequence of aging. A cause is found in approximately 80 percent of elderly patients. The most common causes of anemia in the elderly are chronic disease and iron deficiency. Vitamin B12 deficiency, folate deficiency, gastrointestinal bleeding and myelodysplastic syndrome are among other causes of anemia in the elderly. Serum ferritin is the most useful test to differentiate iron deficiency anemia from anemia of chronic disease. Not all cases of vitamin B12 deficiency can be identified by low serum levels. The serum methylmalonic acid level may be useful for diagnosis of vitamin B12 deficiency. Vitamin B12 deficiency is effectively treated with oral vitamin B12 supplementation. Folate deficiency is treated with 1 mg of folic acid daily.