Vitamin D and UV exposure in chronic kidney disease

Abstract

With loss of renal function and decreasing glomerula filtration rate the serum levels of 25-hydroxyvitamin D [25(OH)D] as well as 1,25-dihydroxyvitamin D [1,25 (OH)2 D] often decrease simultaneously. In representative groups of German patients on renal replacement therapy (hemodialysis, peritoneal dialysis, kidney transplantation) our group retrospectively analyzed the vitamin D status over a period of 12 y (1995‒2006). Only 11% of patients had a serum level of 25(OH)D that was > 30 ng/ml, more than 70% had a level of 25(OH)D < 20 ng/ml. In clinical trials we used sun-simulating artificial lamps to produce vitamin D3 in the skin. Partial-body irradiation (15% of body surface) was used during the routine hemodialysis treatment. Whole-body UV exposure was done in a standing position three times a week before the hemodialysis treatment. With both procedures we observed an increase of the serum level of 25(OH)2D3 by approx. 35-50% over a period of 2‒3 mo, maintenance of trabecular bone mineral density and a normalization of systolic and diastolic blood pressure. Heart rate variability improved during the whole-body radiation intervention period by 20‒25%. Patients who continued the whole-body irradiation regularly two or three times before starting the routine hemodialysis session had maintained normal levels of circulating 25(OH)D3 and of 1,25(OH)2D3. Therefore, from our data it can be recommended that intermittent suberythemal UVB exposure with a sun-simulation spectrum is effective to treat and/or protect against vitamin D deficiency in chronic and end-stage kidney disease patients.

Keywords: 1,25-Dihydroxyvitamin D; 25-Hydroxyvitamin D; bone mineral density; chronic kidney disease; hypertension; vitamin D3.

Figure 1. Vitamin D Status of German Hemodialysis Patients (Medians over the time course 1995 – 2006)

Figure 2. Vitamin D Status and Mortality in German Hemodialysis Patients (Medians over the time course 1995–2006)

Figure 3. Partial-body UV irradiation during a routine hemodialysis session (from 46, with permission)

Figure 4. Sun-simulating UV irradiation cabin (from 46, with permission)

Figure 5. Vitamin D Metabolite Levels in Hemodialysis Patients after Whole-Body UV Irradiation

Figure 6. Vitamin D Metabolite Levels in Hemodialysis Patients after Partial-Body Irradiation (approx. 15% of Body Surface)

Figure 7. Trabecular Bone Mineral Density (DE-QCT) of Hemodialysis Patients before and after 6 Months of Whole-Body UV Irradiation

Figure 8. Heart Rate, Systolic and Diastolic Blood Pressure at Rest and at Maximal Work Load of Hemodialysis Patients before and after 6 Months of Whole-Body UV Irradiation

Figure 9. Heart Rate Variability (ECG-RR-Differences and SD(dRR)) of Hemodialysis Patients before and after 6 Months of Whole-Body UV Irradiation