Meri J. Ala-Houhala, Toni Karppinen, Katja Vähävihu, Hannu Kautiainen, Yvonne Dombrowski, Erna Snellman, Jürgen Schauber, Timo Reunala
DOI: 10.2340/00015555-1685

A course of treatment with narrow-band ultraviolet B (NB-UVB) improves psoriasis and increases serum 25-hydroxyvitamin D (25(OH)D). In this study 12 patients with psoriasis who were supplemented with oral cholecalciferol, 20 µg daily, were given a course of NB-UVB and their response measured. At baseline, serum 25(OH)D was 74.14±22.9 nmol/l. At the 9th exposure to NB-UVB 25(OH)D had increased by 13.2 nmol/l (95% confidence interval (95% CI) 7.2–18.4) and at the 18th exposure by 49.4 nmol/l (95% CI 35.9–64.6) above baseline. Psoriasis Area Severity Index score improved from 8.7±3.5 to 4.5±2.0 (p<0.001). At baseline, psoriasis lesions showed low vitamin D metabolizing enzyme (CYP27A1, CYP27B1) and high human-defensin-2 mRNA expression levels compared with those of the healthy subjects. In conclusion, NB-UVB treatment significantly increases serum 25(OH)D in patients with psoriasis who are taking oral vitamin D supplementation, and the concentrations remain far from the toxicity level. Healing psoriasis lesions show similar mRNA expression of vitamin D metabolizing enzymes, but higher antimicrobial peptide levels than NB-UVB-treated skin in healthy subjects.