Vitamin D and narrowband ultraviolet B phototherapy for chronic kidney disease-associated pruritus.

Background: In addition to improving the serum vitamin D balance, narrowband ultraviolet B (NB-UVB) phototherapy can effectively treat chronic kidney disease-associated pruritus (CKD-aP). We investigated the degree of CKD-aP amelioration according to changes in the serum vitamin D level after NB-UVB phototherapy.

Methods: This was a before-after clinical study in patients with refractory CKD-aP on hemodialysis. NB-UVB phototherapy was administered thrice weekly for 12 weeks. The response of CKD-aP to NB-UVB phototherapy was assessed as the change in pruritus intensity over time. A rapid response was defined as a reduction in the visual analog scale (VAS) score of ≥50% within the first 6 weeks of NB-UVB phototherapy.

Results: We included 34 patients in this study. Although serum 25-hydroxy vitamin D [25(OH)D] concentrations increased significantly, by a median of 17.4 ng/mL, after the phototherapy course, other serologic parameters did not change. NB-UVB phototherapy reduced the VAS score for pruritus intensity over time significantly more in patients with Δ25(OH)D of >17.4 ng/mL than in patients with Δ25(OH)D of ≤17.4 ng/mL (p = 0.001). Ten patients were rapid responders. Multivariate logistic regression analysis showed that Δ25(OH)D was independently associated with rapid response (odds ratio, 1.29; 95% confidence interval, 1.02-1.63; p = 0.04).

Conclusion: The effect of NB-UVB phototherapy on patients with CKD-aP correlated with their increase in serum vitamin D levels. Further well-designed clinical and experimental studies are needed to clarify the relationship between NB-UVB phototherapy and serum vitamin D levels in patients with CKD-aP.