Isotope-dilution assay for urinary methylmalonic acid in the diagnosis of vitamin B12 deficiency. A prospective clinical evaluation

Journal Article · Fri May 01 00:00:00 EDT 1987 · Ann. Intern. Med.; (United States)

DOI:https://doi.org/10.7326/0003-4819-106-5-707· OSTI ID:6520874

Matchar, D B; Feussner, J R; Millington, D S; Wilkinson, Jr, R H; Watson, D J; Gale, D

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.

• Research Organization: Durham VA Medical Center, NC
• OSTI ID: 6520874
• Journal Information: Ann. Intern. Med.; (United States), Vol. 5
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
MALONIC ACID
BIOASSAY
VITAMIN B-12
NUTRITIONAL DEFICIENCY
DIAGNOSIS
GAS CHROMATOGRAPHY
ISOTOPE DILUTION
MASS SPECTROSCOPY
PATIENTS
URINE
BIOLOGICAL MATERIALS
BIOLOGICAL WASTES
BODY FLUIDS
CARBOXYLIC ACIDS
CHROMATOGRAPHY
DICARBOXYLIC ACIDS
DRUGS
HEMATINICS
HEMATOLOGIC AGENTS
ISOTOPE APPLICATIONS
MATERIALS
ORGANIC ACIDS
ORGANIC COMPOUNDS
SEPARATION PROCESSES
SPECTROSCOPY
TRACER TECHNIQUES
VITAMIN B GROUP
VITAMINS
WASTES
550901* - Pathology- Tracer Techniques