Vitamin D Deficiency and Its Hematological Correlates in Patients with Sickle Cell Disease at a Ugandan Clinic.

PURPOSE: To determine the prevalence of vitamin D deficiency (VDD), evaluate its correlation with key hematological parameters, and identify associated factors among patients attending the Sickle Cell Clinic at Mengo Hospital (Kampala, Uganda). PATIENTS AND METHODS: This cross-sectional study enrolled 213 patients with sickle cell disease (SCD) at Mengo Hospital, serum 25-hydroxyvitamin D levels were measured. Levels were classified as deficient (<20 ng/mL) or sufficient (≥20 ng/mL). Hematological indices, red blood cell (RBC) count, hemoglobin (Hb), and red cell distribution width-coefficient of variation (RDW-CV) were assessed using an automated analyzer, and Spearman correlation was used to assess correlations with vitamin D levels. Multivariable Poisson regression identified variables associated with vitamin D deficiency (VDD), reporting outcomes as adjusted prevalence ratios (aPR). RESULTS: The median age was 10 years (IQR 5-13); 50.7% were male. The prevalence of vitamin D deficiency (VDD) was 47.4% (95% CI 40.8-54.2%). Weak but significant positive correlations were observed between serum vitamin D levels and RBC count (ρ = 0.170, p = 0.013) and Hb concentration (ρ = 0.157, p = 0.022), while a negative correlation was noted with RDW-CV (ρ = -0.162, p = 0.018). Adolescents and adults had a higher prevalence of VDD compared to younger children (12-17 years; aPR 1.96, p = 0.002) and (≥ 18 years; aPR 3.20, p < 0.001) respectively. Additionally, folic acid and hydroxyurea were associated with a lower risk of VDD (aPR 0.69, p = 0.028). CONCLUSION: Nearly half of the patients with sickle cell disease had vitamin D deficiency. Older age increased the risk. VDD is weakly but significantly associated with lower Hb/RBC and higher RDW, suggesting a possible contributory role in the hematologic profile of Ugandan SCD patients.