Serum cobalamin, folate, methylmalonic acid and total homocysteine as vitamin B12 and folate tissue deficiency markers amongst elderly Swedes--a population-based study.

OBJECTIVES: The possibilities of detecting tissue cobalamin and folate deficiency are under debate. In this report the levels of serum cobalamin, folate, methylmalonic acid (MMA) and total homocysteine (tHcy) and their interrelations in a representative random population sample are presented.
DESIGN: Cohort study.
SETTING: A general mid-Swedish population.
SUBJECTS: A 20% random sample of persons 70 years or older in a defined geographical area were invited to a survey. A total of 235 (85%) persons responded, out of whom 224 had no interfering diseases. MAIN OUTCOME MEASURES: Serum cobalamin, folate, MMA and tHcy.
RESULTS: The serum levels of cobalamin, folate, MMA and tHcy were all correlated to cobalamin and folic acid treatment. They were also correlated to the intake of multivitamin preparations. In addition, serum cobalamin was higher in untreated women than in men but not correlated to age. Serum folate was correlated neither to sex nor age. Serum tHcy and MMA were both directly correlated to age but MMA not to sex. MMA was inversely correlated to serum cobalamin but not to serum folate, whereas serum tHcy was inversely correlated to serum cobalamin, folate and creatinine. Neither serum cobalamin, folate, MMA nor tHcy had any significant correlation to haemoglobin, erythrocyte volume fraction (EVF) or mean red cell volume. Half of the study population had abnormal MMA or tHcy levels, suggesting a latent or overt tissue deficiency of cobalamin or folate.
CONCLUSIONS: A substantial proportion of the elderly general population had signs of low tissue levels of cobalamin or folate. Amongst those who took multivitamin preparations this proportion was much lower.