Déficit de vitamina B12


1: Am Fam Physician 2003;67:979-86 [Texto completo]

Vitamin B12 Deficiency

Oh RC, Brown DL.

Army Health Clinic, Darmstadt, Germany and USA, Madigan Army Medical Center, Fort Lewis, Washington

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.


2: Clin Lab Med  2002 Jun;22(2):435-45

Modern approaches to the investigation of vitamin B12 deficiency.

Ward PC.

Department of Pathology and Laboratory Medicine, University of Minnesota, Duluth School of Medicine, 10 University Drive, Duluth, MN 55812, USA.

The classic workup of a patient for possible PA is revisited in light of the vanishing Schilling test. The vagaries of testing for B12 and blocking antibodies are reexamined. The advantages and disadvantages of newer tests such as MMA and serum gastrin levels are catalogued. At this juncture in the evolution of new test strategies, there is a considerable controversy regarding the significance of high MMA levels in the face of normal B12 levels, particularly in the elderly. Hopefully, this controversy will soon be resolved and the newer crop of tests will be proven and accepted in the workplace. Still, the words of Alexander Pope spring to mind: "Be not the first by whom the new are tried, Nor yet the last to lay the old aside."

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3: Ann Pharmacother  2002 Jul-Aug;36(7-8):1268-72

Treatment of vitamin b(12)-deficiency anemia: oral versus parenteral therapy.

Lane LA, Rojas-Fernandez C.

College of Pharmacy, The University of Oklahoma Health Sciences Center, Norman Regional Hospital, Norman, OK, USA.

OBJECTIVE: To evaluate the use of oral cyanocobalamin therapy in the treatment of cobalamin (vitamin B(12))-deficient anemia. DATA SOURCES: Primary and review articles were identified by MEDLINE search (1966-May 2000) and through secondary sources. DATA SYNTHESIS: Cobalamin-deficient anemia is among the most common diagnoses in older populations. Cobalamin-deficient anemia may be diagnosed as pernicious anemia, resulting from the lack of intrinsic factor required for cobalamin absorption or as protein malabsorption from the inability to displace cobalamin from protein food sources. Several studies provide evidence that daily oral cyanocobalamin as opposed to monthly parenteral formulations may adequately treat both types of cobalamin-deficient anemias. CONCLUSIONS: Daily oral cyanocobalamin at doses of 1000-2000 microg can be used for treatment in most cobalamin-deficient patients who can tolerate oral supplementation. There are inadequate data at the present time to support the use of oral cyanocobalamin replacement in patients with severe neurologic involvement.

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4: Neurology  2002 May 28;58(10):1572-3

Symptoms of B12 deficiency can occur in women of child bearing age supplemented with folate.

Drazkowski J, Sirven J, Blum D.

Department of Neurology Comprehensive Epilepsy Program, Mayo Clinic, Scottsdale,

AZ 85259, USA.

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5: Adv Exp Med Biol  2002;503:57-67

Impact of vitamin B-12 deficiency during lactation on maternal and infant health.

Allen LH.

Department of Nutrition, University of California, Davis 95616, USA.

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6: Mayo Clin Proc  2002 Mar;77(3):291-4 [Texto completo en formato PDF]

Reversible myelopathy in a 34-year-old man with vitamin B12 deficiency.

Pittock SJ, Payne TA, Harper CM.

Department of Neurology, Mayo Clinic, Rochester, Minn 55905, USA.

Vitamin B12 deficiency is common, with most patients lacking classic features of advanced severe deficiency. Early diagnosis and treatment prevent severe anemia and irreversible damage to the nervous system. We describe a 34-year-old man with pernicious anemia who presented with clinical and radiologic features of early myelopathy and borderline low serum levels of vitamin B12. Prompt diagnosis based on the measurement of serum methylmalonic acid and treatment with cyanocobalamin injections led to rapid resolution of clinical manifestations and magnetic resonance imaging abnormalities. We review the literature of magnetic resonance imaging in vitamin B12 deficiency myelopathy and discuss the issues relating to diagnosis and early treatment of this potentially reversible condition.


7: Postgrad Med  2001 Jul;110(1):99-105; quiz 106 [Texto completo]

Approaches to vitamin B12 deficiency. Early treatment may prevent devastating complications.

Dharmarajan TS, Norkus EP.

Division of Geriatrics, Our Lady of Mercy Medical Center, 4141 Carpenter Ave, Bronx, NY 10466, USA.

Vitamin B12 deficiency is a common problem that affects the general population and the elderly in particular. Persons with the deficiency may be asymptomatic or may have hematologic or neuropsychiatric signs and symptoms. If the disorder is untreated, complications may cause significant morbidity. In this article, Drs Dharmarajan and Norkus discuss approaches to screening and diagnosis as well as the nontoxic, low-cost treatments now available.

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8: J Pediatr  2001 Jan;138(1):10-7

Vitamin B12 deficiency in children and adolescents.

Rasmussen SA, Fernhoff PM, Scanlon KS.

Division of Birth Defects, Child Development, and Disability and Health, National Center for Environmental Health, Atlanta, Georgia, USA.

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9: Hematol Oncol Clin North Am  2000 Oct;14(5):1079-100, viii

Clinical and laboratory features and sequelae of deficiency of folic acid (folate) and vitamin B12 (cobalamin) in pregnancy and gynecology.

Frenkel EP, Yardley DA.

Department of Internal Medicine, University of Texas Southwestern Medical Center at Dallas, USA.

Classically, deficiency of folic acid (folate) or vitamin B12 (cobalamin) was recognized by the presence of a macrocytic anemia resulting from megaloblastic changes in the bone marrow. A markedly changing paradigm has identified both new mechanisms for altered folate and cobalamin status and new sequelae and clinical interrelationships that include altered mechanisms of absorption, a changing pattern of neurologic deficits, an increased risk of vascular occlusive lesions, and an important relationship with the mechanisms of neoplastic transformation. Several of these newer characterizations relate to issues of neoplasia in the nonpregnant woman and to issues in pregnancy, such as the potential for developmental abnormalities of the fetal nervous system.

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