Comparison of zinc protoporphyrin concentration in capillary whole blood and venous washed red blood cells among young Burkinabe children

Abstract

BackgroundZinc protoporphyrin (ZPP) is a useful indicator of iron (Fe) status. Washing red blood cells (RBC) prior to ZPP analysis has been advised to avoid false positives in individuals with malaria, but this procedure adds complexity to sample processing.ObjectiveTo compare ZPP in capillary whole blood samples (ZPPcap) and washed RBCs from venous blood (ZPPven) among young Burkinabe children in a malaria endemic region.MethodsCapillary and venous lithium‐heparinized blood samples were collected within 0–4 d in children aged 9 mo (n=592). The RBCs of venous samples were washed twice using saline solution. ZPPcap and ZPPven concentrations were assessed by hematofluorometer (AVIV). Malaria was identified using HRP‐II rapid diagnostic test, and presence of inflammation was based on C‐reactive protein (CRP ≥5 mg/L) and/or α‐1‐acid glycoprotein (AGP ≥1 g/L).ResultsThe median (range) of ZPPcap and ZPPven were 212.3 (20.3–1526.7) and 136.5 (11.5–1455.5) μmol/mol heme, respectively. The mean ZPPcap is higher than the mean ZPPven (p<0.0001), but the log transformed ZPPcap and ZPPven concentrations are highly correlated even in the presence of malaria and inflammation (r=0.88–0.92; p<0.0001).ConclusionUnwashed whole blood can be used to determine Fe deficiency by ZPP, even in the presence of malaria or inflammation.Funded by the Bill & Melinda Gates Foundation.