Screening for cobalamin deficiency in geriatric outpatients: prevalence and influence of synthetic cobalamin intake.

OBJECTIVES: To describe the prevalence of cobalamin (Cbl) deficiency in older adult outpatients and to determine whether regular intake of a synthetic source of cobalamin confers protection against Cbl deficiency.
DESIGN: Cross-sectional study.
SETTING: Two university-affiliated geriatric medicine outpatient clinics. PARTICIPANTS: Three hundred fifteen older adults (age range 65-100) without a history of previously diagnosed or treated Cbl deficiency, severe anemia, or a life-threatening illness. MEASUREMENTS: Detailed information on total synthetic Cbl intake (from vitamins, fortified cereal, and supplemental nutritional formula sources) and laboratory measures of serum Cbl, metabolite panel (serum methylmalonic acid, homocysteine, cystathionine, and 2-methylcitric acid), complete blood count, and serum creatinine levels.
RESULTS: Cbl deficiency (serum Cbl < or =300 pg/mL and methylmalonic acid (MMA)>271 nmol/L) was found in 13% of screened patients. Forty-six percent of screened patients reported regularly taking a source of synthetic Cbl. Serum Cbl correlated with synthetic Cbl intake, and patients regularly taking synthetic Cbl were significantly less likely to be Cbl deficient than persons not taking supplemental Cbl (8% vs 17%, P =.02).
CONCLUSION: Regular use of a multivitamin/synthetic Cbl source confers some degree of protection against Cbl deficiency in older adults. The relatively high prevalence rates and benefit of synthetic Cbl intake in this study reinforce recommendations that older adults should be screened for Cbl deficiency and should incorporate synthetic sources of Cbl as part of a balanced diet. Appropriate screening intervals and the optimal dose of supplemental Cbl to prevent Cbl deficiency remains to be determined.