Influence of serum 25-hydroxyvitamin D on the rate of pain episodes in Nigerian children with sickle cell anaemia.

BACKGROUND: In sickle cell disease (SCD), symptoms of vitamin D deficiency (VDD) and chronic pain can overlap.

AIM: To examine the relationship between serum vitamin D levels and the frequency of acute pain episodes.

METHODS: In this cross-sectional study, serum 25-hydroxyvitamin D (25-OHD) was assayed by high-performance liquid chromatography, and its influence on the number of significant pain episodes was examined by bivariate and logistic regression analyses.

RESULTS: The mean (SD) serum 25-OHD level in 123 children with SCD (HbSS) was 105.8 (24.1) nmol/L (range 37.5-155.8). Fourteen patients (11.4%) either had a deficient (1.6%) or insufficient (9.8%) level. None had severe VDD. All the children with sub-optimal vitamin D experienced pain, as did 69.7% of those with normal vitamin D [14 (100%) vs 76 (69.7%), 95% CI 0.7-0.9, p = 0.04]. The mean serum vitamin D level in the 90 patients with at least one pain episode [103.1 (25.2) nmol/L] was significantly lower than the 113.1 (19.3) nmol/L in the 33 without a pain episode (95% CI 1.3-7.8, p = 0.04). The frequency of pain correlated inversely with the serum 25-OHD level. Serum levels of vitamin D (OR 1.2, 95% CI 1.3-1.7, p = 0.04) and fetal haemoglobin concentration (OR 1.6, 95% CI 1.1-1.4, p = 0.02) predicted significant pain episodes.

CONCLUSION: In children with SCD, there is a possible association between depressed serum vitamin D levels and increased frequency of acute pain episodes. Vitamin D supplements should be considered in patients with low levels and frequent episodes of pain.