Red cell basic ferritin content of patients with megaloblastic anaemia due to vitamin B12 or folate deficiency

The basic ferritin content of red cells was measured in patients with untreated megaloblastic anaemia. The red cell ferritin of 10 patients with anaemia and vitamin B12 deficiency (mean 579, range 68-2616 attogram (ag)/cell); and of 8 patients with folate deficiency (mean 792, range 141-2373 ag/cell) were significantly elevated (P less than 0.001) compared with normal subjects (mean 10.7, range 4-47 ag/cell) and showed a significant correlation with pre-treatment levels of plasma ferritin and less so with percent transferrin saturation. Following vitamin replacement elevated red cell ferritin levels decreased during the period of reticulocytosis and was normal in 9 patients evaluated after 6 months. The magnitude of increase in red cell basic ferritin levels observed in untreated megaloblastic anaemia is comparable to that of subjects with idiopathic haemochromatosis and suggests that interpretation of this index for iron overload should take into consideration concomitant body folate or vitamin B12 status.