Methylmalonic acid quantification by stable isotope dilution gas chromatography mass spectrometry from filter paper urine samples

A specific method for quantification of methylmalonic acid (MMA) from urine samples dried onto filter paper is described, The method involves stable isotope dilution gas chromatography-mass spectrometry with [methyl-H-2(3)]-MMA as the internal standard, MMA is stable in dry paper samples stored at room temperature for at least 2 weeks, The extraction efficiency of MMA from paper was 56-58%. The concentration of urinary MMA in dried filter paper specimens from 190 normal controls was 1.21 +/- 1.34 (mean +/- SD) mmol/mol of urinary creatinine, Age-related reference values are also reported, The concentrations, normalized to the urinary creatinine concentration, decrease with age, The applicability of this method to rapid screening for cobalamin (vitamin B-12)-related disorders and methylmalonic aciduria is demonstrated.