Impact on UVB Narrow Band and UVA1 Therapy on Serum 25-hydroxyvitamin D Levels

This is an open observational study in dermatological patients undergoing phototherapy.

In patients with a skin disease and the routinely given indication for a phototherapy with UVB narrow-band (UVB nb, 311nm) or UVA1 (340-400 nm), the serum 25-hydroxyvitamin D, calcium, parathormone, phosphate and albumin levels will be measured before, during and after completion of the 12-week therapy (30 patients per group). Patients will be recruited in the department of dermatology of the University Hospital Zürich in the outpatient clinic. Following oral and written consent, serum 25-hydroxyvitamin D, calcium, parathormone, phosphate and albumin levels will be measured before the therapy, one week after start as well as after completion of the UVB nb/UVA1 therapy.

In parallel to the study the patients will be asked to fill in a questionnaire evaluating the daily vitamin D consume (milk and milk products, fish, food enhanced in vitamin D, multivitamin supplements), sun exposure per week during previous weeks, degree of tanning, the use of sunscreen, the DLQI and Skindex-29.

A physical examination including clinical score where available will be performed at every "checkpoint". During the first physical examination the Fitzpatrick-skin type of patient will be recorded.

The following participant characteristics will be recorded: age, weight, body mass index (BMI), phototype, skin disease, comorbidities, usual medication, and period of the year where UVB nb/UVA1 therapy is performed (summer vs. winter), cumulative UVB nb/UVA1 doses.