[Effect of ultraviolet irradiation on renal osteopathy in patients in the chronic hemodialysis program]

Under influence of the ultraviolet radiation the formerly lowered 25-hydroxycholecalciferol (25-OH-CC) level increases in persons with healthy kidneys. Such investigations were not yet carried out in patients undergoing dialysis. Since the insufficiency of active vitamin-D-metabolites plays an essential role in the development of the renal osteopathy, since 1978 in 13 patients undergoing dialysis a regular ultraviolet radiation has been performed, in order to stimulate the cutaneous vitamin-D-production. The time of observation was 31.7 +/- 14.3 months. Deionized water served for the production of dialysate. The calcium content was about 3.5 +/- 3.8 mval/l. The patients had very rarely bone and joint complaints. Severe clinical complications of renal osteopathy developed only in one female patient in the 3rd year of dialysis with a fracture of the neck of the femur as well as in a 2nd patient after transplantation of a kidney with permanently progressing demineralization and spondylitis. Controls of the courses showed only in 18.2% a progressing loss of the peripheral mineral content of the bones. The alkaline phosphatase was not increased, the alkaline bone phosphatase appeared with low and not provable activities. A suppression of the secondary hyperparathyroidism could not be proved. Parathormone was increased with 2.30 +/- 1.90 micrograms/l. The 25-OH-CC-levels were normal or slightly increased with 39.1 +/- 12.4 micrograms/l, whereas they were essentially lower in a comparative group without ultraviolet radiation. Therefore in connection with the very low rate of complications of the renal osteopathy with normalized 25-OH-CC-levels new therapeutic possibilities were the result in patients undergoing dialysis after ultraviolet radiation. The increasing importance consists also in the fact that 90% of the human vitamin-D-need are supplied via skin and it was proved by animal experiments that also after bilateral nephrectomy the formation of the active vitamin-D-metabolite 1,25-dihydroxycholecalciferol is possible by photosynthesis.