Comparative Effectiveness of a Six-Week Treatment Course of Vitamin D(2) and D(3) in Children With Sickle Cell Anemia in Steady State With Hypovitaminosis D: A Randomized Clinical Trial

BACKGROUND: Correction of vitamin D deficiency through administration of either vitamin D(2) or D(3) has been shown to reduce chronic bone pains and frequency of acute bone pains, increase bone density as well as improve growth stature in children with sickle cell anemia (SCA). Findings vary on the effectiveness of the two forms of the vitamin. The current study was carried out to compare the effectiveness of a 6-week treatment course of vitamin D(2) and D(3) in the correction of hypovitaminosis D (vitamin D insufficiency and deficiency) as well as evaluate treatment response to derangement of serum calcium and alkaline phosphatase (ALP) in children with SCA in steady state. METHODS: The study was a randomized, double-blind clinical trial of 174 children with SCA aged 1 - 18 years. Subjects with hypovitaminosis D (baseline serum 25-hydroxyvitamin D (25(OH)D) below 75 nmol/L) were randomized into two treatment arms. Each arm treated either of the two forms of vitamin D had a once weekly dose of 50,000 IU for a period of 6 weeks. RESULTS: Median rise in serum 25(OH)D after 6 weeks of oral vitamin D(2) or D(3) was similar between the two groups (median rise in 25(OH)D of 17.8 nmol/L in D(2), 15.3 nmol/L in D(3) groups). Also, there was no significant difference in the proportion of subjects that improved in their vitamin D status in both treatment arms (P = 0.409). Treatment was significantly associated with increase in proportion of subjects with normal serum calcium (P ≤ 0.001) and decrease in proportion of subjects with elevated serum ALP (P ≤ 0.001). CONCLUSION: Once weekly dose (50,000 IU) of either vitamin D supplement has equal effectiveness in correction of hypovitaminosis D. However, vitamin D(3) may be cost-effective because it is cheaper.