The incidence of
macrocytic anemia has been investigated in 32 patients on maintenance
hemodialysis (mean age 46 years, mean duration of dialysis treatment 27.5 months), in 18 patients with combined
hemodialysis (HD) and
hemofiltration (HF) treatment (mean age 42 years, mean duration of combined HD and HF treatment 6.3 months) and in 32 patients after
renal transplantation (mean age 41 years, mean observation period since successful
renal transplantation 55.2 months). Also investigated were serum levels of
vitamin B12 (radioassay kit 57Co) and
folic acid (radioassay kit 125J). Macrocytosis (MCV greater than 96 fl) was observed in 38% of the patients on maintenance
hemodialysis, in 44% of the patients with combined HD and HF treatment, and in 47% of the renal transplant recipients. In the chronically dialysed patients, in contrast to the patients with combined HD and HF treatment, the mean serum
folic acid level was significantly lower (p less than 0.005) than that of healthy controls. Serum levels of
vitamin B12 were within the normal range in all patients. There were no significant differences in serum levels of
folic acid and
vitamin B12 between the patients with MCV greater than 96 fl and MCV less than or equal to 96 fl. Nor was there a correlation between the serum levels of
folic acid or
vitamin B12 and mean corpuscular volume. These results suggest that
folic acid deficiency is of minor importance in the complex pathogenesis of
anemia in hemodialysed patients.