Partial Body UV Exposure in Chronic Kidney Disease and Extrarenal Vitamin D Metabolism

Exposure of the skin to sunshine is the major natural source of vitamin D. In order to imitate this natural production of vitamin D for patients with chronic kidney disease, hemodialysis patients were exposed three times a week to radiation of the front part of both legs to normalize the vitamin D status.

Partial body UVB irradiation was performed during the routine dialysis session. Twenty-two patients took part, with a mean age of 61.7 (range=35-81) years.

Serum levels of 25(OH)D₃ and 1,25(OH)₂D₃ increased into the mid normal range. Intact parathyroid hormone decreased by 25% and osteocalcin by 45%. 24-Hour blood-pressure monitoring demonstrated decreases in systolic and diastolic blood pressure.

Partial body exposure to UVB radiation normalized not only the serum level of 25(OH)D₃, but also that of 1,25(OH)₂D₃, which resulted in a significant decrease in parathyroid hormone, osteocalcin levels, and also in blood pressure. Sunshine imitating UVB exposure utilizes the capacity of the skin to convert extrarenally vitamin D₃ to 25(OH)D₃ and 1,25(OH)₂D₃.