RAPID DIAGNOSIS OF Fe DEFICIENCY BY MEASUREMENT OF FREE ERYTHROCYTE PORPHYRINS (FEP)

Abstract

Inadequate Fe supply to the bone marrow results in an increased level of FEP in the peripheral blood. FEP concentration may be measured easily in blood samples collected on Guthrie paper by a micromethod developed in this laboratory (Ped. Res. 6: 366, 1972). This study investigated the use of FEP to assess the body Fe stores. Normal values in 48 adult males were 1.42 ± .45 μg FEP/g Hgb. Values above 2.8 μg FEP/g Hgb (mean ± 3 s.d.) were considered elevated. FEP were measured in 151 children with normal blood Pb (< 30 μg/100 ml) and transferrin saturation (TS) between 2 and 35%. FEP were found elevated in 21/21 children with Fe deficiency anemia (Hgb < 9 g%); in 13/14 children with TS 2-8%; in 40/53 children with TS 9-15%; in 18/43 children with TS 16-25% and in 5/20 children with TS 26-35%. The logarithm of the FEP concentration was inversely correlated with the TS, indicating that the FEP level increases exponentially as the body Fe stores become depleted. The FEP levels were elevated also in 7/12 cases of sickle cell anemia and in 5/16 cases of chronic infections, but normal in 11/11 cases of β-thalassemia trait. These data indicate that FEP levels in the peripheral blood reflect the body Fe stores. Elevation of FEP detects Fe deficiency before anemia develops; normal FEP level discriminates thalassemia trait from Fe deficiency. FEP levels provide a diagnosis of Fe deficiency by finger puncture.