Correlation Between Low- Iron Formula Use and Lower than Average Iron Status as Evaluated by Hematocrit

Abstract

Approximately 10% of WIC infants in RI, require physician ordered, non-contract formulas, which include low-iron formula. To investigate if this use of low-iron formula might have a detrimental effect upon the hematocrit values of these infants a retrospective analysis was conducted comparing hematocrit values of infants receiving low-iron and iron-fortified formula at 6 and 12 months of age. Hematocrits were measured using the standard capillary collection technique by trained WIC staff. The subjects were selected with the following criteria : full term delivery, no hematologic or metabolic complications, birth weight of at least 6lb., received low-iron formula for at least 4 consecutive months, and hematocrit data were available at both 6 and 12 months of age. Of the 92 charts initially screened 75 met these criteria and were matched with a control group of infants receiving iron-fortified formula. The infants were paired by agency, age, race and gender.The prevalence of anemia (as defined by Hct < or = 33%) at 6 and 12 months was compared using Chi square analyses. There was no difference in the proportion of anemic children at six months. (27% of the low-iron group and 17% of the iron-fortified group). Significantly more low-iron formula infants were anemic at 12 months (17%) compared to me infants receiving iron-fortified formula (3%), (Chi square = 7.4, P< .01). There was also no difference in mean hematocrit values at 6 months comparing the infants receiving low-iron formula (M = 34.7+/− 2.4) to the infants receiving iron-fortified formula (M = 35.0 +/− 2.3) (t = 0.7, P = 0.60). At 12 months of age, however, the difference between the two groups was statistically significant with the low-iron group having lower hematocrits (M = 35.1 +/− 2.3) than the iron-fortified group (M = 35.9 +/− 1.9) (t = 5.3, P = 0.02).These results appear to support the need for iron-fortified formula throughout the first year of life. The relatively high proportion of anemic children at six months not receiving iron-fortified formula suggests that more intensive education of providers may be necessary.