High risk of vitamin D deficiency in children with sickle cell disease.

Vitamin D is a particularly concerning nutrient for children with homozygous SS sickle cell disease (SCD-SS) due to their increased skin melanin concentrations, reduced levels of physical activity, and poor vitamin D intake. The goal of this study was to compare the vitamin D status of children with SCD-SS to healthy African-American children living in the same geographic area. Growth, dietary intake, serum 25-hydroxyvitamin D [25(OH)D], and intact parathyroid hormone (iPTH) concentrations were measured in 61 African-American subjects with SCD-SS and 89 healthy African-American control subjects age 5 to 18 years from the Philadelphia, PA, region (latitude 39.95 degrees N). Median serum 25(OH)D concentrations were 15 ng/mL (95% confidence interval [CI]: 13, 17) in subjects with SCD-SS and 21 ng/mL (95% CI: 18, 22) in healthy control subjects (P<0.0002). Vitamin D deficiency [25(OH)D<11 mg/mL] was found in 33% of subjects with SCD-SS and 9% of healthy control subjects (P<0.001); 25% of subjects with SCD-SS and 17% of healthy control subjects had elevated iPTH [(>59 rhog/mL), P<0.05]. Ninety-three percent of subjects with SCD-SS and 90% of healthy subjects had vitamin D insufficiency [25(OH)D<30 mg/mL]. The risk of vitamin D deficiency among subjects with SCD-SS was 5.3 (95% CI: 2.5, 8.2) times greater than control subjects, adjusted for season and age. Poor vitamin D status was prevalent in children with SCD-SS and healthy African-American children living in the same geographic area. However, children with SCD-SS were at greater risk for vitamin D deficiency than healthy African-American children.