Methylmalonic acid analysis using urine filter paper samples to screen for metabolic vitamin B 12 deficiency in older adults.

Aim: Methylmalonic acid (MMA) analysis in urine represents a noninvasive approach to screening for vitamin B 12 deficiency in older adults. A method allowing the analysis of MMA/creatinine in fasting urine collected on filter paper was developed/validated. Method: Dry urine specimens were eluted using a solution containing internal standards, filtrated and analyzed by ultra-performance LC-MS/MS. Results: The method allowed the chromatographic separation of MMA from succinic acid. Dried urine samples were stable for 86 days at room temperature. The MMA/creatinine ratios measured in urine collected on filter paper were highly correlated with values derived from the corresponding liquid specimens. Conclusion: This robust filter paper method might greatly improve the accessibility and cost-effectiveness of vitamin B 12 deficiency screening in older adults.