Zinc protoporphyrin and iron deficiency screening: trends and therapeutic response in an urban pediatric center.

Importance: Iron deficiency is the most common micronutrient deficiency among children worldwide, with iron-deficiency anemia associated with long-term adverse neurodevelopmental effects. Objective: To understand the role of zinc protoporphyrin (ZPP) in iron deficiency screening in a low-income pediatric population, as well as to describe the prevalence and trends of abnormal ZPP and the response to iron therapy. Design: Retrospective longitudinal study of data from electronic medical records collected from January 1, 2002, through December 31, 2010. Setting: Boston Medical Center primary care center. Participants: A total of 2612 children with baseline routine screening results for complete blood cell count, lead, and ZPP drawn between ages 8 and 18 months and at follow-up were included. Children with sickle cell disease or lead toxicity were excluded. Intervention: Documented iron prescription. Main Outcome Measure: Reduction of baseline abnormal ZPP at follow-up. Results: Of 2612 children, 48% had an abnormal ZPP level at baseline. Among those with abnormal ZPP (n = 1254), 18% were prescribed iron. Iron prescription was significantly associated with ZPP reduction (odds ratio, 1.5; 95% CI, 1.1 to 2.0) and greater mean change in ZPP (mean difference, -4.4; 95% CI, -7.2 to -1.5). In multivariate analysis, the effect of iron prescription on the reduction of abnormal ZPP was modified by hemoglobin level. Iron prescription was significantly associated with ZPP reduction among those with anemia (odds ratio, 2.4; 95% CI, 1.1 to 5.0). Iron was rarely prescribed in children without anemia; a substantial, but not statistically significant, trend to improvement in those prescribed iron with low-normal hemoglobin was found. Conclusions and Relevance: Abnormal ZPP was common in this low-income population. Iron prescription was significantly associated with a larger reduction of ZPP. Our data suggest that ZPP may be appropriate for iron deficiency screening; further investigation is warranted to explore the role of ZPP among nonanemic children.