Examining the Clinical Usefulness of Urine Methylmalonic Acid for Diagnosis of Vitamin B-12 Deficiency in Older Adults: A Pilot Study

Charlotte Bédard-Delisle,1,2 Guillaume Leonard,1,2 Christiane Auray-Blais,1,3 Isabelle Reid,2 Mohamed Gamrani,1,3 Hassiba Chebbihi,1,2 Nancy Presse1,2, †1Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, Quebec, Canada; 2Research Centre on Aging, CIUSSS de L’Estrie-CHUS, Sherbrooke, Quebec, Canada; 3Centre Hospitalier Universitaire de Sherbrooke Research Center, CIUSSS de l’Estrie-CHUS, Sherbrooke, Quebec, Canada†Nancy Presse passed away on February 7, 2025Correspondence: Guillaume Leonard, Research Centre on Aging, CIUSSS de L’Estrie-CHUS, 1036 rue Belvedere Sud, Sherbrooke, Quebec, J1H 4C4, Canada, Tel +1 819 821 2220 ext. 45246, Fax +1 819 829 7141, Email [email protected]: Vitamin B-12 deficiency is common among older adults and can lead to irreversible neurological damage and severe complications if not treated early. Despite its clinical significance, effective management remains challenging due to the absence of simple and sensitive biomarkers for early detection and for monitoring treatment response.Purpose: This pilot study evaluated the feasibility and potential of the urinary methylmalonic acid (uMMA)/creatinine ratio as a biomarker of vitamin B-12 deficiency in older adults, while exploring clinical responses following supplementation.Participants and Methods: A 3-month quasi-experimental pre-post study was conducted with 53 community-dwelling adults aged ≥ 70 years. Participants provided 4 monthly fasting urine samples to enable tandem mass spectrometry analysis of the uMMA/creatinine ratio before and after 1200 μg/day of peroral vitamin B-12 supplementation. Balance (Berg Balance Scale, Activities-specific Balance Confidence Scale), cognitive function (Montreal Cognitive Assessment), and neurophysiological markers (motor evoked potentials [MEP] latency) were assessed before and after supplementation.Results: All urine filter paper samples were successfully received and analyzed, with most participants (n = 45) maintaining a supplementation adherence rate of 95% or higher. Supplementation led to a statistically significant reduction in uMMA/creatinine levels, accompanied by significant improvements in both balance and cognitive performance. A significant correlation was observed between the reduction in the uMMA/creatinine ratio and cognitive improvement. No significant changes were detected in MEP latency.Conclusion: Urinary methylmalonic acid is a promising biomarker for assessing vitamin B-12 deficiency and treatment response in older adults. Larger, well-designed studies with extended supplementation periods are needed to confirm its clinical utility and better evaluate the impact of prolonged supplementation on balance, cognitive and neurophysiological outcomes.Keywords: vitamin B-12 deficiency, aging, methylmalonic acid, cognition, transcranial magnetic stimulation, motor evoked potential