Dr. Ron’s Research Review – January 30, 2013

This week’s research review focuses on Vitamin B12 deficiency.

Cobalamin deficiency is common in elderly patients; most cite the prevalence at about 12% from the Framingham study. Many elderly with "normal" serum vitamin concentrations are metabolically deficient in cobalamin or folate. (Lindenbaum, Rosenberg et al. 1994)

Serum cobalamin concentrations < 258 pmol/L were found in 222 subjects (40.5%) compared with 17.9% of younger control subjects (P < 0.001).

Serum methylmalonic acid and total homocysteine concentrations were elevated in association with cobalamin values < 258 in 11.3% and 5.7%, respectively, of the cohort.

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. (Oh and Brown 2003)

The nearly ubiquitous use of gastric acid–blocking agents, which can lead to decreased vitamin B12 levels, may have an underappreciated role in the development of vitamin B12 deficiency. Taking the widespread use of these agents and the aging of the U.S. population into consideration, the actual prevalence of vitamin B12 deficiency may be even higher than statistics indicate. (Oh and Brown 2003)

First described by Carmel in 1995, food- cobalamin malabsorption is frequent in elderly people, and is characterized by the inability of the body to release cobalamin from food or intestinal transport proteins, particularly in the presence of hypochlorhydria, where the absorption of ‘unbound’ cobalamin is normal. (Fernandez-Banares, Monzon et al. 2009)

Dr. Ron


Articles

A short review of malabsorption and anemia

            (Fernandez-Banares, Monzon et al. 2009) Download

Anemia is a frequent finding in most diseases which cause malabsorption. The most frequent etiology is the combination of iron and vitamin B12 deficiency. Celiac disease is frequently diagnosed in patients referred for evaluation of iron deficiency anemia (IDA), being reported in 1.8%-14.6% of patients. Therefore, duodenal biopsies should be taken during endoscopy if no obvious cause of iron deficiency (ID) can be found. Cobalamin deficiency occurs frequently among elderly patients, but it is often unrecognized because the clinical manifestations are subtle; it is caused primarily by food-cobalamin malabsorption and pernicious anemia. The classic treatment of cobalamin deficiency has been parenteral administration of the vitamin. Recent data suggest that alternative routes of cobalamin administration (oral and nasal) may be useful in some cases. Anemia is a frequent complication of gastrectomy, and has been often described after bariatric surgery. It has been shown that banding procedures which maintain digestive continuity with the antrum and duodenum are associated with low rates of ID. Helicobacter pylori (H. pylori) infection may be considered as a risk factor for IDA, mainly in groups with high demands for iron, such as some children and adolescents. Further controlled trials are needed before making solid recommendations about H. pylori eradication in these cases.

Prevalence of cobalamin deficiency in the Framingham elderly population

            (Lindenbaum, Rosenberg et al. 1994) Download

To determine whether the increased prevalence of low serum cobalamin concentrations in elderly people represents true deficiency, serum concentrations of cobalamin and folate and of metabolites that are sensitive indicators of cobalamin deficiency were measured in 548 surviving members of the original Framingham Study cohort. Serum cobalamin concentrations < 258 pmol/L were found in 222 subjects (40.5%) compared with 17.9% of younger control subjects (P < 0.001). Serum methylmalonic acid and total homocysteine concentrations were markedly elevated in association with cobalamin values < 258 pmol/L in 11.3% and 5.7%, respectively, of the cohort. Both metabolites were increased in 3.8% of the cohort, associated with significantly lower erythrocyte counts and higher mean cell volumes. Serum metabolites correlated best with serum cobalamin values, even when subnormal determinations were excluded. The prevalence of cobalamin deficiency was > or = 12% in a large sample of free-living elderly Americans. Many elderly people with "normal" serum vitamin concentrations are metabolically deficient in cobalamin or folate.


Vitamin B12 deficiency

            (Oh and Brown 2003) Download

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.

References

Fernandez-Banares, F., H. Monzon, et al. (2009). "A short review of malabsorption and anemia." World J Gastroenterol 15(37): 4644-52 PMID: 19787827

Lindenbaum, J., I. H. Rosenberg, et al. (1994). "Prevalence of cobalamin deficiency in the Framingham elderly population." Am J Clin Nutr 60(1): 2-11 PMID: 8017332

Oh, R. and D. L. Brown (2003). "Vitamin B12 deficiency." Am Fam Physician 67(5): 979-86 PMID: 12643357