Evaluation of serum levels of calcium and phosphorus in uremic pruritus patients before and after narrow band ultraviolet B phototherapy

Background Pruritus is one of the most common skin alterations associated with chronic renal disease (CRD). Narrow band ultraviolet B (NB-UVB) is considered an effective and safe treatment modality for those patients. Objective The objective of this study was to evaluate the effect of NB-UVB on serum calcium (Ca) and phosphorus (P) as possible pruritogenic substances in uremic patients. Patients and methods In 40 patients with CRD-related pruritus and receiving regular hemodialysis (group A) serum levels of Ca, P, and Ca–P product were determined. The results were compared with positive controls of another 40 patients with CRD without pruritus and receiving regular hemodialysis (group B). Group A, patients with pruritus, was treated with totalbody NB-UVB phototherapy 3 times/week for 6 weeks, with assessments of pruritus using a visual analog scale score before and after the end of the sessions and at monthly intervals for 3 months after completion of the sessions. Estimation of serum levels of Ca, P, and Ca–P product was carried out and compared with the levels before phototherapy. Results Significantly higher serum levels of both P and Ca–P product were present in patients with CRD-related pruritus in comparison with their matched controls without pruritus. Serum Ca level was not significantly different between the two groups. After 6 weeks of NB-UVB, there was a significant reduction in the pruritus score (Po0.01), which was associated with a significant decrease in the serum levels of P and Ca–P product. Whereas the mean serum Ca level of all patients did not show a statistically significant difference after NB-UVB therapy (P= 0.312), a significantly higher percentage of patients showed normalization of their Ca level after phototherapy (74.3 vs. 32.5%, P= 0.004). Conclusion NB-UVB is an effective and safe treatment option in alleviating pruritus associated with CRD, with a possible effect of normalizing serum levels of both Ca and P. This highlights the role of Ca and P as expected pruritogenic substances in the appearance of itch in CRD patients.