title: The effect of ultraviolet B radiation treatments on calcium excretion and vitamin D metabolites in kidney stone formers.
abstract: Several factors could explain the effect of warm, sunny weather on kidney stone formation. To determine the role of sun exposure, we used a light box to administer artificial ultraviolet B radiation during the winter months in New York City. Eleven male stone formers and 7 age- and sex-matched controls received 10 UVB light exposures over a two-week period while maintaining a 400 mg calcium diet. 25-OH vitamin D levels increased significantly (p less than 0.001) in both patients (25.9 +/- 9.8 to 51.6 +/- 14.1 ng/ml) and controls (21.3 +/- 7.1 to 49.6 +/- 3.1 ng/ml). However, 1,25 dihydroxyvitamin D levels rose in the patients (50.8 +/- 14.8 to 55.9 +/- 13.1 pg/ml) but fell (60.1 +/- 6.5 to 49.4 +/- 3.1 pg/ml) in the controls. Only 2 of the 11 patients but all of the controls demonstrated this down regulation of 1,25 dihydroxyvitamin D levels (p less than 0.002). 24,25 dihydroxyvitamin D levels tended to rise in both groups but parathyroid hormone levels were unchanged. There was a trend, which did not reach statistical significance, for parameters of calcium excretion to increase after UVB radiation. 24-hour urinary calcium excretion rose 24% from 140 to 173 mg in the patients and 31% from 113 to 148 mg in the controls. The ratio of calcium/creatinine following a one gram calcium load showed a small increase after UVB radiation from 0.17 to 0.20 in patients and 0.118 to 0.124 in the controls. However, no correlation could be discerned between changes in vitamin D metabolite concentrations and changes in urinary calcium.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Department of Medicine, Cornell University, School of Medicine, New York, NY 10021.
authors.forename: M
authors.initials: M
authors.lastname: Varghese
authors.forename: J S
authors.initials: JS
authors.lastname: Rodman
authors.forename: J J
authors.initials: JJ
authors.lastname: Williams
authors.forename: A
authors.initials: A
authors.lastname: Brown
authors.forename: D M
authors.initials: DM
authors.lastname: Carter
authors.forename: J E
authors.initials: JE
authors.lastname: Zerwekh
authors.forename: C Y
authors.initials: CY
authors.lastname: Pak
mesh_terms: D000328:Adult; D002118:Calcium / Q000652:urine*; D002136:Calcium, Dietary / Q000008:administration & dosage; D005260:Female; D006801:Humans; D006887:Hydroxycholecalciferols / Q000097:blood*; D007669:Kidney Calculi / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D010281:Parathyroid Hormone / Q000097:blood; D012621:Seasons; D014466:Ultraviolet Rays / Q000009:adverse effects*
chemical_list: D002136:Calcium, Dietary; D006887:Hydroxycholecalciferols; D010281:Parathyroid Hormone; D002118:Calcium