title: Urinary excretion of 25-hydroxyvitamin D in health and the nephrotic syndrome.
abstract: Patients with the nephrotic syndrome may exhibit low serum 25-OH-D concentrations. We developed a method for isolation of 25-OH-D from urine, with measurement by competitive binding assay. Daily urinary 25-OH-D excretion in healthy subjects averaged 0.17 +/- 0.15 nmol/day. Among nephrotic patients, urinary 25-OH-D excretion ranged from 0.27 to 10 nmol/day, in direct relation to the severity of proteinuria (r=0.76) and averaged 3.7 +/- 3.5 nmol/day. The 25-OH-D in the urine of nephrotic patients was unconjugated, implying that it was excreted with the serum VDBG, which has been shown to have a molecular weight and isoelectric point similar to that of albumin. We conclude that low serum 25-OH-D concentrations among nephrotic patients are principally the result or urinary losses of steroid. (J Lab Clin Med 99:325, 1982.)
mesh_terms: D015652:25-Hydroxyvitamin D 2; D000328:Adult; D000368:Aged; D003404:Creatinine / Q000378:metabolism; D004872:Ergocalciferols / Q000031:analogs & derivatives* / Q000652:urine; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009404:Nephrotic Syndrome / Q000652:urine*; D011507:Proteinuria / Q000378:metabolism; D012709:Serum Albumin / Q000378:metabolism
chemical_list: D004872:Ergocalciferols; D012709:Serum Albumin; D015652:25-Hydroxyvitamin D 2; D003404:Creatinine