Anemia is defined as a hemoglobin concentration or hematocrit less
than the 5th percentile of the distribution in a non-iron deficient
reference population specific for age, sex, and stage of pregnancy
for women and age and sex for children.
The reference population for anemia was based on the third National
Health and Nutrition Examination Survey (NHANES III), which excluded
persons who had a high likelihood of iron deficiency. Age, sex, and
stage of pregnancy specific hemoglobin and hematocrit cutoff values
for anemia are based on the 5th percentile from NHANES III for both
children and women. In the reference population about 5 percent of
the population is expected to fall below the 5th percentile for
anemia due to normal biologic variation. Prevalence of anemia
greater than the expected 5 percent based on the reference
population may indicate that anemia is a health problem in the
population. |