Classification of microcytic anemia by fluorometric analysis of free erythrocyte porphyrins (FEP).

Microcytic red blood cells (RBC) occur in iron-deficiency anemia, lead poisoning, and the thalassemia syndromes. Micromeasurement of FEP by acid extraction from RBC was performed on RBC of 64 subjects with RBC mean corpuscular volume less than 78 fl as determined on a Coulter S. FEP was also determined on RBC from 25 nonanemic, normocytic subjects for comparison. The 25 nonanemic subjects, 29 subjects with alpha-thalassemia trait and 16 subjects with beta-thalassemia trait had FEP less than 107 mugm/100 ml RBC. Nineteen microcytic subjects with iron-deficiency anemia had FEP of 185--752 mugm/100 ml RBC. Hemolysates from 8 lead intoxication individuals had FEP values similar to those of iron-deficient patients. The fluorescence emission spectra of lysates with high FEP, which were not extracted, were similar in iron deficiency and lead poisoning. The porphyrin that accumulates in these two conditions appears to be zinc protoporphyrin. Micromeasurement of FEP can be used to initially classify microcytic anemias into either a disturbance of globin synthesis or a disturbance in heme synthesis. Iron-deficiency anemia and lead poisoning cause accumulation of identical prophyrin and cannot be distinguished by fluorometric analysis.