Direct fluorometric determination of erythrocyte free and zinc protoporphyrins in health and disease.

Overview

Precise estimation of erythrocyte non-iron fluorescent protoporphyrins in conditions where small variations in their level are involved is experimentally difficult. We used a highly sensitive fluorometric procedure which provided, in a single direct measurement, the differential estimation of the levels of free (FPP) or zinc (ZPP) protoporphyrins relative to the hemoglobin (Hgb) concentration in diluted blood samples. With use of an internal calibration procedure, the levels of ZPP and FPP in normal healthy donors were found to be 2.7 +/- 0.9 and 0.20 +/- 0.08 micrograms/g Hgb, respectively. In blood samples taken from patients suffering from acute inflammatory processes the mean ZPP level was twofold higher, and the mean FPP was four times higher, than the normal level, suggesting better sensitivity of the FPP measurement for the detection of minor influences on the hemopoietic system. In a variety of non-inflammatory diseases FPP was less but still significantly above normal level. No significant correlation was found between the levels of both protoporphyrins and Hgb concentrations in all the groups of normal donors and patients examined.