THE MICROMEASUREMENT OF FREE ERYTHROCYTE PORPHYRIN (FEP) AS A MEANS OF DIFFERENTIATING ALPHA-THALASSEMIA TRAIT FROM IRON DEFICIENCY ANEMIA

Abstract

Microcytosis occurs in children with iron deficiency anemia, lead poisoning and thalassemia. To differentiate these disorders, it has been necessary to quantitatively measure serum iron, transferrin saturation, serum lead levels, hemoglobin A2 and F levels. Piomelli has screened for lead poisoning and Oski has differentiated beta-thalassemia from iron deficiency anemia by measuring free erythrocyte porphyrins (FEP). We have used the micromeasurement of FEP to differentiate alphathalassemia from iron deficiency. The method used is a modification of that described by Piomelli et al. (Pediatrics 51: 254, 1973). Eighteen individuals with previously diagnosed alpha-thalassemia have had FEP and serum iron and transferrin saturation levels determined. Twelve individuals with alpha-thalassemia and normal transferrin saturation studies had FEP below 90 ugms/100 ml of Rbc's. Six individuals with documented iron deficiency and alphathalassemia had FEP greater than 130 ugms/100 ml as did individuals with uncomplicated iron deficiency. Micromeasurement of Rbc FEP provides a rapid means of differentiating iron deficiency from thalassemia with normal transferrin saturations. However, when alphathalassemia and iron deficiency occur together, alphathalassemia cannot be proven until the iron deficiency is corrected.