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UVB, UVA/UVB narrowband phototherapies increased serum 25(OH)D
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Dermatologic patients had a significant increase in serum 25-hydroxyvitamin-D3 levels after phototherapy with narrowband ultraviolet B and ultraviolet A/narrowband ultraviolet B radiation, according to study results.
Researchers in Switzerland conducted an observational study at Zurich University Hospital from April 2009 to February 2011, and measured serum 25-hydroxyvitamin-D3 (25[OH]D), calcium, parathormone, phosphate and albumin before therapy, 2 weeks after initiating therapy and upon completion of phototherapy. One hundred sixteen patients (median age, 49.7 years; 62 men) underwent therapy with ultraviolet (UV) A1 (n=38), UVA/narrowband UVB (UVA/UVBnb; n=30) or UVBnb (n=48) two or three times weekly for 53 to 90 days. Four diagnosis groups were determined: atopic dermatitis, psoriasis, morphea and others.
Eighty-four participants completed the study. After 12 weeks of treatment, UVBnb phototherapy increased 25(OH)D from 22.1 ng/mL to 39.5 ng/mL (P<.001), and researchers said the lower the baseline value for 25(OH)D, the steeper the increase in 25(OH)D. Patients undergoing UVA/UVBnb therapy also saw serum 25(OH)D increase from 23.9 ng/mL to 50.3 ng/mL (P=.003), while those treated with UVA1 therapy experienced a drop from 21.9 ng/mL to 19 ng/mL (P<.001) during the same period.
Study limitations included no trial randomization, heterogeneous diagnoses that could result in the influence of a specific skin disease, and patient treatment preference.
“Phototherapy has an impact on 25 (OH)D levels in the serum,” the researchers concluded. “UVBnb is a potent inducer of serum 25(OH)D reaching considerable effects already after 2 weeks. Notably, UVA1 therapy led to a decrease in serum 25(OH)D levels, suggesting that wavelength spectrum of photoexposure is important. Our study data call for closer examination of a potential confounding effect of various skin diseases and the need for oral vitamin D supplementation in UVA1-treated patients.”
Disclosure: The researchers report no relevant financial disclosures.
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