CENTRAL ROLE OF ZINC PROTOPORPHYRIN IN STAGING IRON-DEFICIENCY

In iron deficiency, zinc protoporphyrin (ZPP) is produced instead of h eme, and the ZPP concentration in erythrocytes is increased (normal le ss than or equal to 40 mu mol/mol heme). We investigated the relevance of ZPP for staging iron deficiency. ZPP was determined by hematofluor ometry in samples from 103 patients. Nineteen patients with iron deple tion showed decreased serum ferritin (12.1 +/- 4.4 mu g/L) with normal ZPP and hemoglobin (Hb). Twelve patients with iron-deficient erythrop oiesis had decreased ferritin (10.4 +/- 2.4 mu g/L), increased ZPP (72 +/- 9 mu mol/mol heme), and normal Hb concentrations. In 72 patients with iron-deficiency anemia, ferritin was <12 mu g/L. In mild anemia ( Hb between 100 and 120 g/L, and normal erythrocyte indices), ZPP was 1 00 +/- 16 mu mol/mol heme. in severe anemia (Hb <100 g/L, decreased er ythrocyte indices), ZPP values were significantly higher (265 +/- 109 mu mol/mol heme). We conclude that measurements of ZPP, ferritin, and Hb can reliably be combined to classify the degree of iron deficiency.