Failure of hematocrit to detect iron deficiency in infants.

BACKGROUND

Infants of low-income families have three times the risk of iron deficiency as those of families above the poverty level. Psychomotor deficits have been associated with iron deficiency once it produces anemia. High-risk infants are usually screened for iron deficiency between 9 and 12 months of age with a hematocrit measurement. This type of screening may miss iron-deficient infants who are not yet anemic.

METHODS

In the well-child clinics for low-income families in Houston, Texas, a hematocrit (Hct) < or = 33% is the standard screening criterion for iron deficiency. Three hundred twenty-one infants between the ages of 9 and 18 months had capillary blood drawn for Hct testing. Serum ferritin levels were simultaneously measured.

RESULTS

Six (1.9%) of the 321 infants were anemic, but none because of iron deficiency. Fifty-one infants (15.9%) were iron deficient (ferritin <10 micrograms/L), none of whom were anemic. Hematocrit and ferritin levels did not correlate statistically.

CONCLUSIONS

The Hct is not an adequate screening test for iron deficiency in this population of infants. Although this population is usually considered high-risk, iron deficiency was mild. Selective screening of high-risk infants in this population may be appropriate, but a more sensitive screening test is required. Further studies are needed to determine the prevalences of iron deficiency in this and other high-risk populations.