These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Has vitamin D a direct renal effect on the tubular reabsorption of phosphate? A study in parathyroidectomized (PTX) and non-PTX man.
    Author: Madsen S, Olgaard K.
    Journal: Adv Exp Med Biol; 1978; 103():111-23. PubMed ID: 717102.
    Abstract:
    The effect of 1-alpha-hydroxycholecalciferol (1alpha-OH-D3) on the renal handling of phosphate and the immunoreactive parathyroid hormone in serum (i-PTH) has been studied in 10 patients with a wide range of glomerular filtration rate (GFR), maximal tubular reabsorption of phosphate (TmP) and i-PTH. The patients were treated with 2 microgram 1alpha-OH-D3 per day for approximately 80 days. Before and after this period of treatment, the TmP, i-PTH, 51Cr EDTA clearance, extracellular volume, standard bicarbonate, and serum calcium were measured in each patient. The TmP/GFR ratio was used as an index of the renal handling of phosphate. The index increased significantly (mean 26.5%, p less than 0.01) during the treatment, while i-PTH decreased significantly (mean 37.0%, p less than 0.01). A significant inverse correlation was demonstrated between the TmP/GFR index and i-PTH both before (r = -0.87; p less than 0.001) and after (r = -0.79; p less than 0.01) the administration of 1alpha-OH-D3, while none of the other factors investigated were correlated to the index. This may suggest that the stimulating effect of biologically active vitamin D on the tubular reabsorption of phosphate is mediated via the parallel suppression of PTH, but does not exclude that biologically active vitamin D exerts a direct effect on the human renal tubule. Therefore, the effect of 1alpha-OH-D3 was studied in 5 totally parathyroidectomized patients, in whom concomitant suppression of PTH would not occur. Estimation of TmP/GFR was performed 1) when the patients were vitamin D depleted and hypocalcemic, and 2) after 14-27 days of treatment with 1alpha-OH-D3 to obtain stable normocalcemia. In patients with absent parathyroid function, no increasing effect of 1alpha-OH-D3 on TmP/GFR could be demonstrated. It is therefore concluded 1) that 1alpha-OH-D3 exhibits no antiphosphaturic effect in the absence of PTH and 2) that the previously demonstrated antiphosphaturic effect of 1alpha-OH-D3 in man is mediated via a concomitant suppression of PTH.
    [Abstract] [Full Text] [Related] [New Search]