Cobalamin (B12) and
folate deficiency is related to both increased erythrocyte mean cellular volume (MCV) and raised serum total
homocysteine (tHcy) values. Furthermore, there are indications that B12 and
folate serum values do not represent the tissue status of the two
vitamins exactly. Therefore, a direct relationship between MCV and tHcy, if demonstrated, could support the hypothesis that tHcy is a better
indicator for the cited
vitamin status than the serum levels of B12 and
folate. We studied MCV, gamma glutamyl
transferase (GGT), serum B12,
folate and tHcy values in 200 hospitalized patients. There was a significant correlation of MCV with GGT (r = 0.266, P < 0.001) and with tHcy (r = 0.248, P < 0.001), but not with serum B12 and
folate. Stepwise multiple linear regression with MCV as dependent and GGT, B12,
folate and tHcy as independent variables, respectively, revealed significant associations of MCV with GGT (B = 2.18, 95% CI 0.95-3.42, P = 0.001) and tHcy (B = 3.33, 95% CI 1.26-5.39, P = 0.002). By removing tHcy from this model, serum B12 became a significant predictor of MCV (B = -1.70, 95% CI -3.25 to -0.15, P = 0.032). Serum
folate was not significantly associated with MCV in multivariate analysis. In conclusion, the present study confirms indications that serum B12 and
folate values lack clinical sensitivity and specificity in diagnosing
vitamin deficiency states by showing MCV was better associated to tHcy, than to B12 or
folate serum levels. This observation demonstrates that tHcy may be useful in diagnosing patients with B12 and/or
folate deficiency.