The use of zinc protoporphyrin in screening young children for iron deficiency.

The common practice of screening children for iron deficiency with hematocrit (HCT) or hemoglobin detects only those children with iron deficiency severe enough to cause anemia. At 40 cents per test, zinc protoporphyrin (ZPP) can be measured in the physician's office and identify iron deficiency before anemia develops. The purpose of our study was to evaluate ZPP screening in young children by hematofluorimetry. All children between 9 and 36 months old were enrolled over a 1-year period. All children with HCT < 33% or iron deficiency (ZPP > or = 50 mumoles per mole-heme) were treated with ferrous sulfate at 3 mg-Fe/kg/day for 3 months. Four hundred and fifty-eight children were screened with a blood ZPP and spun HCT at entry. Two hundred and forty-three children (53%) had both a normal ZPP and HCT, 155 (34%) had a ZPP > or = 50 and normal HCT, 26 (6%) had a ZPP > or = 50 with HCT < 33%, and 34 (7%) had a normal ZPP and HCT < 33%. Of those with an elevated ZPP and normal HCT, 76% had a therapeutic response to iron therapy, with a 10% decrease in ZPP (P < 0.005). ZPP had a greater sensitivity (81%) than HCT (16%) in identifying children with iron deficiency. ZPP proved to be an effective and inexpensive addition to HCT in identifying children with iron deficiency.