Vitamin D Deficiency In Pediatric Patients with Sickle Cell Disease Correlates with Reticulocytosis but Not with Clinical Disease Severity

Abstract 4820

Vitamin D deficiency is an established phenomenon in both adult and pediatric patients with sickle cell disease. Between 33% and 78% of children and between 60% and 100% of adults with sickle cell disease (HbSS, HbSC, and HbSβ-thalassemia) have been found to have low serum levels of 25-hydroxyvitamin D, the form most clinically useful for measuring total body levels of vitamin D. Proposed factors contributing to low vitamin D levels in these patients include decreased exposure to sunlight secondary to chronic illness and frequent hospitalizations, malnutrition or malabsorption of vitamin D, higher requirements for vitamin D in sickle cell disease, and impaired metabolism of vitamin D. However, very little data has been published demonstrating a correlation between vitamin D deficiency and burden of disease in patients with sickle cell disease. In addition, there is no published data regarding the effect of vitamin D supplementation on patient-oriented outcomes. We retrospectively reviewed the medical records of pediatric patients with sickle cell disease (ages 0–18 years) to evaluate their serum vitamin D levels as a function of red blood cell turnover, patient's age, and factors relating to burden of disease such as number of emergency room visits and hospital admissions related to vaso-occlusive crises. As expected, we found that essentially all of our patients have insufficient levels of vitamin D at baseline. Although no correlation was seen between vitamin D levels and either age or number of hospital visits related to pain crises, reticulocytosis was significantly correlated (p=0.017) with degree of vitamin D deficiency in our patient population in multiple regression analysis. Based on these preliminary data, vitamin D deficiency in patients with sickle cell disease is more likely the result of the disease process as measured by red blood cell turnover as opposed to the previously hypothesized environmental constraints associated with pain crises and frequent hospitalization. Future analysis will be directed at confirming these findings in adult patients and at evaluating the effects of vitamin D supplementation in both adult and pediatric sickle cell patients. Additional studies should also evaluate the pathogenesis of vitamin D deficiency in states of high red blood cell turnover.