Ala-Houhala, Meri J.; Vahavihu, Katja; Snellman, Erna; Hasan, Taina; Kautiainen, Hannu; Karisola, Piia; Dombrowski, Yvonne; Schauber, Jürgen; Saha, Heikki; Reunala, Timo
A Narrow-Band Ultraviolet B Course Improves Vitamin D Balance and Alters Cutaneous CYP27A1 and CYP27B1 mRNA Expression Levels in Haemodialysis Patients Supplemented with Oral Vitamin D.
In: Nephron Clinical Practice, Nr. 1-2: S. 17-22
Background/Aims: Chronic kidney disease (CKD) patients on dialysis areprone to vitamin D insufficiency despite oral vitamin D supplementation.Here, we studied whether narrow-band ultraviolet B (NB-UVB) exposuresimprove vitamin D balance. Methods: 14 haemodialysis patients and 15healthy subjects receiving oral cholecalciferol 20 mu g daily got nineNB-UVB exposures on the entire body. Serum 25-hydroxyvitamin D (25(OH)D)was measured by radioimmunoassay. Cutaneous mRNA expression levels ofCYP27A1 and CYP27B1, two enzymes required for hydroxylation of vitamin Dinto its active metabolite, were also measured. Results: The baselineserum 25(OH)D concentration was 57.6 +/- 18.2 nmol/l in the CKD patientsand 74.3 +/- 14.8 nmol/l in the healthy subjects. The NB-UVB courseincreased serum 25(OH)D by 14.0 nmol/l (95% CI 8.7-19.5) and 17.0nmol/l (CI 13.7-20.2), respectively. At baseline the CKD patients showedsignificantly increased CYP27B1 levels compared to the healthy subjects.Conclusions: A short NB-UVB course is an efficient way to improvevitamin D balance in CKD patients on dialysis who are receiving oralvitamin D supplementation. The increased cutaneous CYP27B1 levels in theCKD patients suggest that the loss of renal activity of this enzyme isat least partially compensated for by the skin.