Reversible C3Hypocomplementaemia in Megaloblastic Anaemia due to Vitamin B12Deficiency

Abstract

Serum C3 [3rd component of complement] and C4 [4th component of complement] levels were determined in patients with Addisonian pernicious anemia (PA) and megaloblastic anemia due to vitamin B12 deficiency from other causes, before and after treatment, in order to study the interaction between vitamin B12 deficiency and complement and the role of complement in the pathogenesis of the gastric lesion of PA. C3 levels are significantly reduced in vitamin B12 deficiency and return to normal on treatment; C3 levels correlate with the degree of anemia but not with serum vitamin B12 levels at diagnosis. C4 levels are normal. The observed C3 hypocomplementemia is apparently not a consequence of immune mechanisms, but may be due to altered synthesis of C3 complement component.