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Isotope-dilution assay for urinary methylmalonic acid in the diagnosis of vitamin B12 deficiency. A prospective clinical evaluation.
Ann Intern Med. 1987 May; 106(5):707-10.AIM

Abstract

Vitamin B12 deficiency is a frequently considered diagnosis for which there is no single, commonly available and accurate test. A urinary methylmalonic acid assay using gas chromatography-mass spectrometry has been proposed as the preferred test. We reviewed vitamin B12 assays on 1599 consecutive patients and prospectively studied all patients with low serum B12 levels (n = 75) and a random sample of patients with normal levels (n = 68). Of 96 evaluable patients, 7 had clinical deficiency. All 7 deficient patients had urinary methylmalonic acid levels greater than 5 micrograms/mg creatine (sensitivity, 100%; confidence interval, 65% to 100%). Of the 89 patients who were not clinically deficient, 88 had urinary methylmalonic acid levels less than or equal to 5 micrograms/mg creatinine (specificity, 99%). The overall test accuracy in this population was 99%. If the high sensitivity and specificity of the gas chromatography-mass spectrometry assay for urinary methylmalonic acid is supported by other clinical studies, the methylmalonic acid assay may become the reference standard for the diagnosis of vitamin B12 deficiency.

Authors

Matchar DB
No affiliation info available
Feussner JR
No affiliation info available
Millington DS
No affiliation info available
Wilkinson RH
No affiliation info available
Watson DJ
No affiliation info available
Gale D
No affiliation info available

MeSH

AgedDeuteriumFemaleGas Chromatography-Mass SpectrometryHumansIndicator Dilution TechniquesMaleMalonatesMethylmalonic AcidMiddle AgedPredictive Value of TestsProspective StudiesVitamin B 12Vitamin B 12 Deficiency

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, Non-P.H.S.

Language

eng

PubMed ID

3551712

Citation

Matchar, D B., et al. "Isotope-dilution Assay for Urinary Methylmalonic Acid in the Diagnosis of Vitamin B12 Deficiency. a Prospective Clinical Evaluation." Annals of Internal Medicine, vol. 106, no. 5, 1987, pp. 707-10.
Matchar DB, Feussner JR, Millington DS, et al. Isotope-dilution assay for urinary methylmalonic acid in the diagnosis of vitamin B12 deficiency. A prospective clinical evaluation. Ann Intern Med. 1987;106(5):707-10.
Matchar, D. B., Feussner, J. R., Millington, D. S., Wilkinson, R. H., Watson, D. J., & Gale, D. (1987). Isotope-dilution assay for urinary methylmalonic acid in the diagnosis of vitamin B12 deficiency. A prospective clinical evaluation. Annals of Internal Medicine, 106(5), 707-10.
Matchar DB, et al. Isotope-dilution Assay for Urinary Methylmalonic Acid in the Diagnosis of Vitamin B12 Deficiency. a Prospective Clinical Evaluation. Ann Intern Med. 1987;106(5):707-10. PubMed PMID: 3551712.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Isotope-dilution assay for urinary methylmalonic acid in the diagnosis of vitamin B12 deficiency. A prospective clinical evaluation. AU - Matchar,D B, AU - Feussner,J R, AU - Millington,D S, AU - Wilkinson,R H,Jr AU - Watson,D J, AU - Gale,D, PY - 1987/5/1/pubmed PY - 2001/3/28/medline PY - 1987/5/1/entrez SP - 707 EP - 10 JF - Annals of internal medicine JO - Ann Intern Med VL - 106 IS - 5 N2 - Vitamin B12 deficiency is a frequently considered diagnosis for which there is no single, commonly available and accurate test. A urinary methylmalonic acid assay using gas chromatography-mass spectrometry has been proposed as the preferred test. We reviewed vitamin B12 assays on 1599 consecutive patients and prospectively studied all patients with low serum B12 levels (n = 75) and a random sample of patients with normal levels (n = 68). Of 96 evaluable patients, 7 had clinical deficiency. All 7 deficient patients had urinary methylmalonic acid levels greater than 5 micrograms/mg creatine (sensitivity, 100%; confidence interval, 65% to 100%). Of the 89 patients who were not clinically deficient, 88 had urinary methylmalonic acid levels less than or equal to 5 micrograms/mg creatinine (specificity, 99%). The overall test accuracy in this population was 99%. If the high sensitivity and specificity of the gas chromatography-mass spectrometry assay for urinary methylmalonic acid is supported by other clinical studies, the methylmalonic acid assay may become the reference standard for the diagnosis of vitamin B12 deficiency. SN - 0003-4819 UR - https://www.unboundmedicine.com/medline/citation/3551712/Isotope_dilution_assay_for_urinary_methylmalonic_acid_in_the_diagnosis_of_vitamin_B12_deficiency__A_prospective_clinical_evaluation_ DB - PRIME DP - Unbound Medicine ER -