Porphyrin biosynthesis in the erythrocytes of patients with sideropenic anaemias.

The ability of erythrocytes to synthesize porphyrins from delta-aminolaevulic acid was compared in healthy people, patients with true iron-deficiency anaemia, and anaemic patients with rheumatoid arthritis. Porphyrin synthesis was found to be impaired in true iron deficiency but not in rheumatoid arthritis cases showing a similar degree of anaemia. The delta-aminolaevulic acid dehydratase activity and the rate of porphobilinogen synthesis did not differ in the three groups studied. The most probable mechanism of impairment of porphyrin synthesis in the anaemia of true iron deficiency seems to be a partial block in the conversion of porphobilinogen into porphyrins. High endogenous and exogenous protoporphyrin concentration did not affect the synthesis of porphyrins.