Effectiveness of zinc protoporphyrin/heme ratio for screening iron deficiency in preschool-aged children

Abstract

Hemoglobin and zinc protoporphyrin (ZPP) tests are commonly used to screen for iron deficiency, but little research has been done to systematically evaluate the sensitivity and specificity of these two tests. The goal of this study was to evaluate the effectiveness of zinc protoporphyrin/heme (ZPP/H) ratio as a point-of-service screening test for iron deficiency among preschool-aged children by comparing the sensitivity and specificity of hemoglobin, ZPP/H ratio, and serum ferritin (SF). Also completed were assessments for the prevalence of anemia, iron deficiency (ID), and iron deficiency anemia (IDA) with indicators of ferritin models. This study was carried out with 95 children ages 3 to 6 y. Anthropometric measurements were assessed, and blood samples were analyzed for hemoglobin, SF, transferrin saturation (TS), and ZPP. Anemia was common and the prevalences of anemia, ID, and IDA were 14.7%, 12.6%, and 5.2%, respectively. The ZPP/H ratio was strongly and significantly correlated with hemoglobin. And ZPP/H ratio was a more sensitive test for ID than hemoglobin or SF measurement, correctly identifying more than twice as many iron-deficient children (sensitivity of 91.7%, compared to 41.7% for hemoglobin and SF). However, ZPP/H ratio had lower specificity (60.2%, compared to 89.1% for hemoglobin or 96.4% for SF) and resulted in the false identification of more subjects who actually were not iron deficient than did hemoglobin or SF. Low hemoglobin concentration is a late-stage indicator of ID, but ZPP/H ratio can detect ID at early stages and can be performed easily at a relatively low cost. Therefore, ZPP/H ratio can serve as a potential screening test for pre-anemic iron deficiency in community pediatric practices.

Impact of Fetal-Neonatal Iron Deficiency on Recognition Memory at 2 Months of Age

“…In the few previous studies of fetal-neonatal iron deficiency and neurodevelopment,(9, 13, 14) cutoffs for low cord-blood ferritin have differed, and other iron status measures have not been used. We therefore measured cord zinc protoporphrin/heme (ZPP/H) ratio as well as cord ferritin, because ZPP/H may be a more sensitive indicator of iron deficiency.…”

Optimizing diagnostic biomarkers of iron deficiency anemia in community-dwelling Indian women and preschool children

“…The ratio of zinc-protoporphyrin/heme (ZPP/H) can be determined rapidly at the point-of-care (POC) by a hematofluorometer. 5 , 6 Serum hepcidin, a key regulator of iron homeostasis, is an important biomarker because its levels determine how well oral iron is absorbed, with low hepcidin levels indicating both a requirement for iron and an ability to utilize it if provided. 7 , 8 …”

“…Although ZPP/H reference values are available for iron deficient pregnant women 5 and children, 6 cut-off values that establish a diagnosis of IDA with acceptable sensitivity and specificity are lacking. Moreover, reference ranges for hepcidin in healthy rural Indian women and children are not defined.…”

Zinc Protoporphyrin and Iron Deficiency Screening

“…32,42,43 False-negative results are common in the setting of inflammation or recent illness, including mild viral infections, further limiting its use for widespread screening. 18,20,21,[44][45][46][47] Other measures suggested in the AAP guidelines were serum transferrin receptor-1 saturation and reticulocyte hemoglobin level, neither of which is routinely available in clinical practice. Zinc protoporphyrin has been used both to screen for lead toxicity and for ID.…”