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Low Cobalamin Levels as Predictors of Cobalamin Deficiency: Importance of Comorbidities Associated with Increased Oxidative Stress.
Am J Med. 2016 Jan; 129(1):115.e9-115.e16.AJ

Abstract

BACKGROUND

Cobalamin (B12) deficiency can lead to irreversible neurocognitive changes if unrecognized. Screening involves measurement of serum cobalamin levels, but the sensitive metabolic indicators of cobalamin deficiency, methylmalonic acid (MMA) and homocysteine (HCys), may be normal when cobalamin values are low and elevated when cobalamin values are normal. Because cobalamin is inactivated by oxidation, the relationship between these metabolites and comorbidities associated with increased oxidative stress (oxidant risks) in subjects with low and low-normal cobalamin levels was studied.

METHODS

A retrospective record-review was conducted of community-dwelling adults evaluated for cobalamin deficiency during a 12-year period with serum cobalamin values in the low (≤ 200 pg/mL; n = 49) or low-normal (201-300 pg/mL; n = 187) range and concurrent measurement of MMA.

RESULTS

When "No" oxidant risk was present, elevated MMA (>250 nmol/L) and HCys (>12.1 μmol/L) values occurred in 50% and 30% of subjects, respectively (P <.01). In contrast, when "Three or More" oxidant risks were present, mean MMA and HCys values were significantly higher, and elevated MMA and HCys values occurred in 84% and 78% of these subjects, respectively (P ≤.012). Pharmacologic doses of cyanocobalamin significantly decreased metabolite values in ≥ 94% of treated subjects.

CONCLUSION

In subjects with low or low-normal cobalamin values, metabolic evidence of cobalamin deficiency is more frequent when 3 or more oxidant risks are present. Thus, defining a low serum cobalamin level to screen for cobalamin deficiency may be a "moving target" due to the variable presence and severity of often subtle, confounding clinical conditions in individual subjects.

Authors+Show Affiliations

Section of Palliative Care, Department of Medicine, Yale University School of Medicine, New Haven, Conn. Electronic address: lawrence.solomon@yale.edu.

Pub Type(s)

Journal Article

Language

eng

PubMed ID

26239093

Citation

Solomon, Lawrence R.. "Low Cobalamin Levels as Predictors of Cobalamin Deficiency: Importance of Comorbidities Associated With Increased Oxidative Stress." The American Journal of Medicine, vol. 129, no. 1, 2016, pp. 115.e9-115.e16.
Solomon LR. Low Cobalamin Levels as Predictors of Cobalamin Deficiency: Importance of Comorbidities Associated with Increased Oxidative Stress. Am J Med. 2016;129(1):115.e9-115.e16.
Solomon, L. R. (2016). Low Cobalamin Levels as Predictors of Cobalamin Deficiency: Importance of Comorbidities Associated with Increased Oxidative Stress. The American Journal of Medicine, 129(1), e9-e16. https://doi.org/10.1016/j.amjmed.2015.07.017
Solomon LR. Low Cobalamin Levels as Predictors of Cobalamin Deficiency: Importance of Comorbidities Associated With Increased Oxidative Stress. Am J Med. 2016;129(1):115.e9-115.e16. PubMed PMID: 26239093.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Low Cobalamin Levels as Predictors of Cobalamin Deficiency: Importance of Comorbidities Associated with Increased Oxidative Stress. A1 - Solomon,Lawrence R, Y1 - 2015/07/31/ PY - 2015/05/12/received PY - 2015/06/30/revised PY - 2015/07/01/accepted PY - 2015/8/5/entrez PY - 2015/8/5/pubmed PY - 2016/4/21/medline KW - Cobalamin KW - Homocysteine KW - Methylmalonic acid KW - Oxidative stress KW - Vitamin B12 SP - 115.e9 EP - 115.e16 JF - The American journal of medicine JO - Am J Med VL - 129 IS - 1 N2 - BACKGROUND: Cobalamin (B12) deficiency can lead to irreversible neurocognitive changes if unrecognized. Screening involves measurement of serum cobalamin levels, but the sensitive metabolic indicators of cobalamin deficiency, methylmalonic acid (MMA) and homocysteine (HCys), may be normal when cobalamin values are low and elevated when cobalamin values are normal. Because cobalamin is inactivated by oxidation, the relationship between these metabolites and comorbidities associated with increased oxidative stress (oxidant risks) in subjects with low and low-normal cobalamin levels was studied. METHODS: A retrospective record-review was conducted of community-dwelling adults evaluated for cobalamin deficiency during a 12-year period with serum cobalamin values in the low (≤ 200 pg/mL; n = 49) or low-normal (201-300 pg/mL; n = 187) range and concurrent measurement of MMA. RESULTS: When "No" oxidant risk was present, elevated MMA (>250 nmol/L) and HCys (>12.1 μmol/L) values occurred in 50% and 30% of subjects, respectively (P <.01). In contrast, when "Three or More" oxidant risks were present, mean MMA and HCys values were significantly higher, and elevated MMA and HCys values occurred in 84% and 78% of these subjects, respectively (P ≤.012). Pharmacologic doses of cyanocobalamin significantly decreased metabolite values in ≥ 94% of treated subjects. CONCLUSION: In subjects with low or low-normal cobalamin values, metabolic evidence of cobalamin deficiency is more frequent when 3 or more oxidant risks are present. Thus, defining a low serum cobalamin level to screen for cobalamin deficiency may be a "moving target" due to the variable presence and severity of often subtle, confounding clinical conditions in individual subjects. SN - 1555-7162 UR - https://www.unboundmedicine.com/medline/citation/26239093/Low_Cobalamin_Levels_as_Predictors_of_Cobalamin_Deficiency:_Importance_of_Comorbidities_Associated_with_Increased_Oxidative_Stress_ L2 - https://linkinghub.elsevier.com/retrieve/pii/S0002-9343(15)00694-4 DB - PRIME DP - Unbound Medicine ER -