Circulating 1,25-Dihydroxycholecalciferol After Intravenous Injections of l{alpha}-Hydroxycholecalciferol in Patients on Regular Haemodialysis |
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Authors: | Papapoulos S E; Berg H vd; Frolich M; Valentijn R M |
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Institution: | 1Clinical Investigation Unit, Department of Endocrinology, University Hospital Leiden TNO, Zeist
2Institute CIVO-Toxicology and Nutrition TNO, Zeist
3Department of Chemical Pathology, University Hospital Leiden The Netherlands
4Department of Nephrology, University Hospital Leiden The Netherlands |
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Abstract: | The formation of 1.25-dihydroxycholecalciferol (1.25-(OH)2D3after single intravenous injections of 1 -hydroxycholecalciferol(1 -OHD3) was examined in four patients with chronic renal failureon regular haemodialysis. Following 13µg 1 -OHD3administered at weekly intervals, 1.25-(OH)2D3 appeared in thecirculation within 1 h, and peak concentrations were reachedbetween 2 h and 5 h. By 8 h serum 1.25-(OH)2D3 concentrationshad started declining and by 44 h they had returned to baselineafter 1µg 1 -OHD3 but they were still above basal after2 and 3 µg by an average of 30 pmol/l. One week afterinjections, concentrations were back to basal in all patientsstudied. The serum 1,25-(OH)2D3 dose response to injected la-OHDwas linear, indicating ample capacity of the liver 25-hydroxylaseto further hydroxylate 1 -OHD. However, examination of the individualresponses revealed lower increments in serum 1.25-(OH)3 concentrationsin the patients with the highest basal serum 25-hydroxyvitaminD concen trations. Intravenous 1 -OHD3 may be useful in the furtherstudy of the interactions between 1.25-(OH)23 calcium and PTHin chronic renal failure, as well as of the hepatic metabolismof vitamin D. |
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Keywords: | Alfacalcidiol Calcitriol Calcium Haemo dialysis Parathyroid hormone Chronic renal failure |
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