Relative Folate Deficiency of Erythrocytes in Pernicious Anemia and Its Correction with Cyanocobalamin.

By Biuu’ ui n A. COOPER AND Louis LOWENSTEIN T HE DETERMINATION of folate activity in serum with Lactobacillus casei allows recognition of patients with folate deficien y.13 It has been observed that much of the L. casei-active folate in human serum consists of N5-methyl tetrahydropteroyl monoglutamate,4 and that the concentration of folate activity in serum is increased in some patients with pernicious anemia in relapse.5 However, not all such patients have high serum folate activity. Determinations of folate activity in whole blood have revealed that folate activity of erytlirocytes is higher than that of serum, but most of the folate activity of erythrocytes is not available for assay with L. casei without preincubation with serum or plasma.6’7 It has been’ reported that whole blood folate activity is decreased in patients with folate deficiency8’9 and in some pateints with pernicious 0