Narrowband UVB treatment increases serum 25-hydroxyvitamin D levels in patients with chronic plaque psoriasis.

The aim of this study was to investigate the effects of narrowband UVB (NB-UVB) phototherapy on serum 25-hydroxyvitamin D (25[OH]D) levels and related parameters in patients with psoriasis. Forty-nine participants with moderate to severe plaque-type psoriasis were included in this study and were treated with NB-UVB therapy 3 times weekly for 6 months or until psoriasis area and severity index (PASI) 75 was achieved. Participants' serum 25(OH)D, calcium, phosphorus, parathyroid hormone (PTH), and alkaline phosphatase (ALP) levels were measured at baseline and completion of treatment, along with PASI scores. We observed that the serum 25(OH)D levels increased after NB-UVB treatment, but the only correlation that was found was the number of sessions of NB-UVB. There was no relationship between patient age, Fitzpatrick skin type, PASI score, or maximum NB-UVB dose and serum 25(OH)D levels.