The Effect of Narrowband UV-B Treatment for Psoriasis on Vitamin D Status During Wintertime in Ireland.

Arch Dermatol. 2010 Aug;146(8):836-42.
Ryan C, Moran B, McKenna MJ, Murray BF, Brady J, Collins P, Rogers S, Kirby B.
BCh, BAO, Baylor Research Institute, 3900 Junius St, Ste 125, Dallas, TX 75246. Caitriona.ryan@baylorhealth.edu.

Objectives To determine whether narrowband UV-B (NB-UV-B) may mediate its beneficial effect on psoriasis by increasing vitamin D levels, and to assess the effect of NB-UV-B on vitamin D status in patients with psoriasis in wintertime.

DESIGN: A prospective controlled study from October 2008 to February 2009.

SETTING: A dermatology outpatient department at a university teaching hospital. Patients Thirty consecutive patients with psoriasis treated with NB-UV-B and 30 control patients with psoriasis were recruited. Control patients were recruited within 1 week of treated patients to control for seasonal variation of serum 25-hydroxyvitamin D 25(OH)D levels. One patient with photoaggravated psoriasis was withdrawn from the study. Intervention Narrowband UV-B was administered 3 times per week. Main Outcome Measure Serum 25(OH)D was measured at baseline, after 4 weeks and at completion of treatment.

RESULTS: Levels of serum 25(OH)D increased significantly (P < .001) from a median (range) of 23 (9-46) ng/mL at baseline to 59 (32-112) 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 (r = 0.61; P < .001) and cumulative UV-B dose (r = 0.47; P = .01) but not with treatment response. At the end of the study, all patients in the treatment group were vitamin D sufficient, but 75% of the control group had vitamin D insufficiency serum 25(OH)D level <20 ng/mL. In a multiple regression model, prior phototherapy was the sole predictor of baseline serum 25(OH)D level (r(2) = 0.13; P = .006), whereas the number of exposures of NB-UV-B predicted change in serum 25(OH)D level (r(2) = 0.38; P = .001).

CONCLUSIONS: Narrowband UV-B effectively increases serum 25(OH)D level while clearing psoriasis. Up to 75% of Irish patients with psoriasis were shown to be vitamin D insufficient during wintertime. PMID: 20713813