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Zinc protoporphyrin/heme as an indicator of iron status in NICU patients
Sandra E Juul1, Joan C Zerzan, Thomas P Strandjord
1Department of Pediatrics, University of Washington, Seattle, Washington 98195, USA. sjuul@u.washington.edu
Insights
The zinc protoporphyrin/heme ratio (ZnPP/H) is higher in newborns than adults and inversely correlates with gestational age. This ratio may indicate a need for additional iron supplementation in certain infant groups.
Area of Science:
- Neonatal Medicine
- Pediatric Hematology
- Biochemistry
Background:
- The zinc protoporphyrin/heme ratio (ZnPP/H) is a validated biomarker for functional iron deficiency in individuals aged 6 months and older.
- Establishing normative ZnPP/H values in neonates is crucial for accurate iron status assessment in this vulnerable population.
Purpose of the Study:
- To determine reference ranges for ZnPP/H in Neonatal Intensive Care Unit (NICU) patients.
- To evaluate the effectiveness of ZnPP/H as an indicator of iron deficiency in neonates.
Main Methods:
- Weekly measurement of ZnPP/H and complete blood counts in NICU patients.
- Documentation of gestational age, growth parameters, iron supplementation, erythropoietin therapy, and blood transfusions.
- Statistical analysis including correlation and significance testing (P <.05).
Main Results:
- A total of 639 ZnPP/H ratios from 143 infants were analyzed.
- ZnPP/H showed a significant inverse correlation with gestational age in the first week of life (r = -0.72, P <.001).
- Maternal diabetes, growth retardation, and chorioamnionitis were linked to elevated ZnPP/H. Iron supplementation and blood transfusions lowered ZnPP/H, while erythropoietin increased it.
Conclusions:
- Newborn infants exhibit higher ZnPP/H ranges compared to adults, with values inversely related to gestational age.
- Elevated ZnPP/H in specific neonatal subpopulations suggests a potential requirement for increased iron supplementation.
Objective:
Zinc protoporphyrin/heme ratio (ZnPP/H) has been well established as an indicator of functional iron deficiency in subjects 6 months of age to adult. The primary objective of this study was to establish normative values for ZnPP/H in NICU patients and secondarily to explore the utility of this test as an indicator of iron deficiency in neonates. Study design ZnPP/H and complete blood counts were obtained weekly on consecutive NICU patients. Gestational age, growth variables, iron supplementation, erythropoietin treatment, and blood transfusions were documented. Results are reported as mean +/- SD. A value of P <.05 was considered significant.
Results:
ZnPP/H ratios (n = 639) were evaluated from 143 infants. During the first week of life, ZnPP/H was inversely correlated with gestational age (n = 78, P <.001, r = -0.72). Maternal diabetes, growth retardation, and exposure to chorioamnionitis were independent risk factors for high ZnPP/H. Both iron supplementation and blood transfusion decreased ZnPP/H (P <.001). Erythropoietin treatment was associated with an increase in reticulocyte count and ZnPP/H (P <.001).
Conclusions:
ZnPP/H is inversely correlated with gestational age, and the range in all newborn infants is higher than in adults. ZnPP/H is elevated in certain infant subpopulations, which suggests that they may require additional iron supplementation.
