Occult cobalamin and folate deficiency in Indians

Our aim was to assess cobalamin and folate levels in normal Indian subjects before undertaking a prospective study of megaloblastic anaemia.

We took samples from 25 men and 25 women to establish the normal range. The exclusion criteria for subjects were age below 18 years and above 65 years, haemoglobin < 12 g/dl, and those who were pregnant, lactating or on any medication including vitamin supplements. A complete blood count and blood film examination for hypersegmented neutrophils were done. Serum cobalamin and folate assays were performed by a competitive immunoassay. The reference range supplied with the kits for serum cobalamin was 100-700 pg/ml and for serum folate it was 3-22 ng/ml.

Since many 'normal' subjects in the sample showed values below the normal reference range, the numbers sampled were increased to 46 men and 50 women. Of all the subjects tested, 46.9% had subnormal values of one of the two vitamins. The normal ranges for serum cobalamin established in this study were--men 100-388 pg/ml and women 105.3-434 pg/ml. Of the 46 men tested, 17 (36.9%) had low cobalamin levels and of the 50 women tested, 23 (46%) had low cobalamin levels. Levels < 50 pg/ml were seen in 46.9% of these subjects. The normal ranges for serum folate in the study were--men 3.1 to > 22 ng/ml, women 3-12.26 ng/ml. In the study group, 8 men (17.3%) and 6 women (12%) had folate deficiency. Eight subjects (17%) had combined deficiency of the two vitamins. The mean corpuscular volume was not informative and was elevated in only 1 subject. Hypersegmentation of neutrophils was present in 75% of deficient subjects.

We established normal levels for serum cobalamin and folate in our study group. Of the subjects studied, 46.9% had subnormal levels of serum cobalamin or serum folate, cobalamin deficiency being five times more common than folate. Hypersegmentation of neutrophils was a better indicator of occult megaloblastosis than the mean corpuscular volume.