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.
Practice Points
- The 25-hydroxyvitamin D (25[OH]D) levels are increased by narrowband UVB (NB-UVB) treatment in psoriasis patients.
- The number of sessions of NB-UVB is associated with increased 25(OH)D levels.
Results
A total of 49 participants (30 [61.22%] males; 19 [38.78%] females) were included in the study. The mean age (SD) was 40.27 (14.62) years (range, 19–74 years). Three (6.12%) participants were Fitzpatrick skin type I, 15 (30.61%) were skin type II, and 31 (63.27%) were skin type III.
The baseline median PASI score for the 49 participants was 10.20 (7.85–13.65). Baseline serum 25(OH)D levels were noted to be deficient in 40 participants (81.63%) and inadequate in 9 participants (18.37%). The distribution of the serum 25(OH)D levels of the participants according to the season was evaluated with the Kruskal-Wallis test and no association was found between serum 25(OH)D levels and seasonal changes (P=.685). Comparison of 25(OH)D basal values with Fitzpatrick skin type revealed a statistically significant relationship between skin type and vitamin D level (P=.024). The basal serum 25(OH)D levels were significantly lower in Fitzpatrick skin type II versus skin type I (P=.039).
Thirty-two (65.31%) participants achieved PASI 75 by the end of treatment. The baseline median PASI score (25th-75th quartiles) for the 32 patients was 10.45 (8.20-13.83) and the posttreatment PASI score was 1.95 (1.20-3.55), a statistically significant decrease following treatment (P<.001)(Table 1). Mean (SD) baseline serum 25(OH)D levels were 14.14 (6.70) ng/mL and posttreatment levels were 46.42 (15.51) ng/mL in these participants, which demonstrated a statistically significant increase during NB-UVB treatment (P<.001). None of the participants reached the toxicity levels (>80 ng/mL) for serum 25(OH)D. There were no significant changes in serum calcium or phosphorus levels posttreatment (Table 1), but statistically significant decreases in serum ALP and PTH levels were noted (P=.001 and P=.019, respectively)(Table 1).
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Participants who completed the study (n=32) received an average (SD) of 30.09 (7.53) sessions of NB-UVB treatment and the mean (SD) MED was 611.88 (240.14) mJ/cm2. The mean (SD) maximum dose was 2090.09 (341.78) mJ/cm2 (Table 2).
Posttreatment serum 25(OH)D levels were compared with the number of NB-UVB phototherapy sessions and the maximum dose values. We found that the posttreatment serum 25(OH)D levels correlated with the number of sessions (P=.031) but not with the maximum dose (P=.498).
Using regression analysis, we also evaluated the effect of the increase in vitamin D levels—posttreatment serum 25(OH)D level minus baseline serum 25(OH)D levels—on the decrease in PASI scores—baseline PASI score minus posttreatment PASI score—and found no effect of serum 25(OH)D level increase on PASI decrease (P=.530). There was no correlation between increased serum 25(OH)D levels and age, Fitzpatrick skin type, or baseline PASI score.
