Zinc protoporphyrin-to-heme ratios in high-risk and preterm infants.
OBJECTIVE
To refine the reference range for the zinc protoporphyrin-to-heme ratio (ZnPP/H) of preterm infants, we assessed the impact of maternal risk factors on ZnPP/H and evaluated the impact of changes in iron supplementation on iron status.


METHODS
The reference range for neonatal ZnPP/H was refined using prospective data from 31 reference infants ≤ 35 weeks' postmenstrual age (PMA) plus retrospective data from 51 infants <30 weeks' PMA, and 59 infants 30-40 weeks' PMA. Cord blood and first week of life values were compared when both were available. The impact of maternal risk factors was assessed by examining prospectively collected ZnPP/H from 48 high-risk infants. The effect of changing iron supplementation guidelines was evaluated by retrospective chart review of serial ZnPP/H from 194 infants.


RESULTS
Cord ZnPP/H was lower at 30-35 weeks' gestation than at 24-26 weeks' gestation (P = .01). Cord ZnPP/H values from insulin-dependent diabetic mothers were elevated compared with reference values. Changing the iron supplementation protocol was not associated with improved ZnPP/H measurements.


CONCLUSIONS
Cord blood and postnatal reference ranges for ZnPP/H are defined. Iron balance depends on a complex interaction of prenatal and postnatal factors.
Nutritional Sciences Program, University of Washington, Seattle, WA 98195-6320, USA.
Carissa F
CF
Cheng
Joan C
JC
Zerzan
Donna B
DB
Johnson
Sandra E
SE
Juul
D005260:Female; D006418:Heme / Q000032:analysis*; D006801:Humans; D007231:Infant, Newborn; D007234:Infant, Premature; D008297:Male; D011446:Prospective Studies; D011524:Protoporphyrins / Q000097:blood*; D012307:Risk Factors
D011524:Protoporphyrins; C017803:zinc protoporphyrin; D006418:Heme