DUBLIN—Narrowband UV-B effectively increased serum 25-hydroxyvitamin D [25(OH)D] levels while clearing psoriasis, according to a prospective controlled study during October 2008 to February 2009 (Arch Dermatol. 2010;146(8):836-842). A total of 30 consecutive patients with psoriasis treated with NB–UV-B and 30 control patients with psoriasis were recruited. Control patients were recruited within one week of treated patients to control for seasonal variation of 25(OH)D levels. Narrowband UV-B was administered three times per week and serum 25(OH)D was measured at baseline, after four weeks and at completion of treatment.
Levels of serum 25(OH)D increased significantly from a median of 23 ng/mL at baseline to 59 ng/mL at the end of NB–UV-B treatment compared with no change in the control group. The change in serum 25(OH)D level correlated with the number of exposures of NB–UV-B and cumulative UV-B dose, but not with treatment response. At the end of the study, all patients in the treatment group were vitamin D sufficient, but 75 percent of the control group had vitamin D. In a multiple regression model, prior phototherapy was the sole predictor of baseline serum 25(OH)D level, whereas the number of exposures of NB–UV-B predicted change in serum 25(OH)D level. Up to 75 percent of Irish patients with psoriasis were shown to be vitamin D insufficient during wintertime