[Folate and vitamin B12 deficiency. Characterization of parameters for early diagnosis]

True vitamin B12/folate deficiency is more common than is currently appreciated; it appears in many guises and the classic hematological features of megaloblastic anaemia are often absent. The single most reliable predictor of megaloblastic anaemia is serum vitamin B12/folate concentration, but this determination in a screening program for all patients is difficult in terms of laboratory overload and cost. Early recognition of nutritional anaemias is, however, mandatory and we undertook this study to explore the possibility of identifying, on a demographic basis or because of routine laboratory results, a group of subjects at risk for vitamin B12/folate deficiency. Results obtained in simultaneous radioassay of serum B12 and folate levels and erythrocyte folate concentration in 1.200 hospitalized patients are presented. Coexisting iron deficiency was excluded by ferritin assay. We found no significant difference between males and females and no correlation between serum folate and B12 concentrations and aging. Low serum folic and cobalamin levels were found in 53% of patients with macrocytosis and elevated MCH, even in the absence of anaemia. These observations suggest that increased MCV and MCH may be present before a related anaemia and that serum folate and cobalamin levels must be monitored early in these patients to prevent a deficiency.