Advanced Age as a Risk Factor for Folate-Associated Functional Cobalamin Deficiency
- Autores: Lawrence R. Solomon
- Localización: Journal of the American Geriatrics Society, ISSN 0002-8614, Vol. 61, Nº. 4, 2013, págs. 577-582
- Idioma: inglés
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Resumen
Objectives: To determine whether high serum folate levels contribute to metabolite changes in elderly subjects with normal cobalamin levels.
Design: Case series.
Setting: Outpatient clinic at a university-based staff model health maintenance organization.
Participants: Two hundred thirty-three ambulatory individuals without diabetes mellitus with normal renal function and normal cobalamin levels evaluated for cobalamin deficiency.
Measurements: Cobalamin, serum folate, methylmalonic acid (MMA), and homocysteine.
Results: Older individuals (?60) with low-normal cobalamin levels (201�300 pg/mL) had higher MMA and lower homocysteine levels when serum folate levels were high (>20 ng/mL) than when serum folate levels were normal (P < .02), but serum folate levels within the normal range were not a determinant of either metabolite. In younger subjects with low-normal cobalamin levels, high serum folate levels were not associated with significant differences in either metabolite. At mid-normal cobalamin levels (301�600 pg/mL), high serum folate levels were associated with lower homocysteine levels in older adults (P < .001) but not with differences in MMA in either age group. Cobalamin therapy decreased or normalized MMA and homocysteine in 89% or more of participants even at pretherapy cobalamin levels greater than 600 pg/mL.
Conclusion: High serum folate levels are associated with higher MMA levels when cobalamin levels are low-normal, and this effect is age dependent, not progressive within the normal serum folate range (suggesting a threshold effect), and reversed by cobalamin therapy. Because MMA may be neurotoxic, these findings suggest caution in the use of folic acid supplements in elderly adults.
