Growth curves for children with sickle cell anemia receiving extended hydroxyurea therapy. The 3rd (▪), 50th (▴), and 97th (•) percentiles for healthy children are illustrated as dotted lines, while the patients (♦) are illustrated as a solid line. Boys increased their average growth rate during hydroxyurea therapy from the 25th percentile for weight and 40th percentile for height to about the 50th percentile for both weight and height after 4 years of hydroxyurea therapy. Girls maintained average growth rates during the treatment period.