Pediatric reference ranges for zinc protoporphyrin

Objectives To determine pediatric reference ranges for zinc protoporphyrin (ZPP). Design and methods The study was conducted in a large pediatric hospital on patient blood specimens (n = 6,478) (0–17 y) accrued from January 2001 to June 2002. The data was analyzed employing the Hoffman approach, which was computer adapted. Results and conclusions The 2.5th and 97.5th percentiles for children age 0 to 12 months were 9 to 40 μg/dL (16.6–73.6 μmol/mol heme) for female subjects and 8.5 to 34.5 μg/dL (15.6–63.5 μmol/mol heme) for males. The 97.5th percentiles decreased for the 13 to 24 months age group for females (32 μg/dL) (58.9 μmol/mol heme). There was a significant decrease in the 97.5th percentile for zinc protoporphyrin (ZPP) concentrations for the 5 to 9 yr age group, the 97.5th percentile being 30 μg/dL (55.2 μmol/mol heme) in both genders, which increased to 33.5 μg/dL (61.6 μmol/mol heme) in the 10 to 17 yr female age group but not for the males (31.5 μg/dL) (58.0 μmol/mol heme). The highest medians were 25.5 μg/dL (46.9 μmol/mol heme) for females, and 21.5 μg/dL (39.6 μmol/mol heme) for males in the 0 to 12 months age group.