Prospective Investigation of 25(OH)D3 Serum Concentration Following UVB Narrow Band Phototherapy in Patients with Psoriasis and Atopic Dermatitis

Abstract

Vitamin D deficiency represents a major health issue. It is a worldwide endemic and is associated with a broad variety of severe diseases. The skin is a key tissue for the human body's vitamin D endocrine system. It represents a target tissue for biologically active vitamin D metabolites. Approximately 90% of the human body's requirements of vitamin D have to be synthesised in the skin by the action of UVB-radiation. However, individual factors that influence a person's cutaneous synthesis of vitamin D are still not well understood. In our present prospective study we investigated the effect of UVB narrow band (UVBnb, 311 nm) and PUVA phototherapy on 25(OH)D3 serum concentration, in patients with psoriasis, atopic dermatitis and a few cases with other dermatoses (n=41). We found that two weeks of UVBnb treatment resulted in an increase of 25(OH)D3 serum concentration from 11.4 to 20.5 ng/ml (p<0.001), while in contrast PUVA-treatment did not significantly alter vitamin D status. These findings question the hypothesis of a relevant vitamin D metabolizing effect of UVA. Psoriasis patients showed a trend for a stronger increase in 25(OH)D3 serum levels following UVBnb compared to patients with atopic dermatitis. Patients with relatively low baseline serum 25(OH)D3 concentrations had a stronger increase in 25(OH)D3 concentrations compared to patients with relatively high 25(OH)D serum concentrations. In general patients with skin types (Fitzpatrick) I and II (median=14.3 ng/ml) had a higher baseline of 25(OH)D3 serum concentration compared to patients with skin types III (median=11.2 ng/ml) or IV-V (median=12.3 ng/ml), although these differences were not statistically significant (p=0.106). Baseline 25(OH)D3 serum concentrations were correlated with presence of genetic variants (SNPs of VDR, CYP2R1, VDBP/GC) that influence vitamin D status, and with other individual factors such as body mass index, age and gender. We also investigated the effect of phototherapy on blood pressure and a variety of laboratory parameters such as CRP, HbA1c, LDL, HDL, triglycerides and cholesterol. In conclusion, our pilot study shows that UVBnb phototherapy efficiently increases 25(OH)D3 serum concentration and reports interesting preliminary findings that have to be re-evaluated in larger follow-up studies.

Keywords: 25(OH)D3 serum concentration; UVB narrow band phototherapy; atopic dermatitis; psoriasis.