Vasopressin regulates renal calcium excretion in humansReport as inadecuate

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* Corresponding author 1 Des Maladies Rénales Rares aux Maladies Fréquentes, Remodelage et Réparation 2 Service d-Explorations fonctionnelles multidisciplinaires CHU Tenon

Abstract : Antidiuretic hormone or arginine vasopressin AVP increases water reabsorption in the collecting ducts of the kidney. Three decades ago, experimental models have shown that AVP may increase calcium reabsorption in rat kidney. The objective of this study was to assess whether AVP modulates renal calcium excretion in humans. We analyzed calcium, potassium, and sodium fractional excretion in eight patients affected by insipidus diabetes nephrogenic or central under acute vasopressin receptor agonist action and in 10 patients undergoing oral water load test affected or not by inappropriate antidiuretic hormone secretion SIADH. Synthetic V2 receptor agonist dDAVP reduced significantly calcium fractional excretion from 1.71% to 0.58% P < 0.05 in patients with central diabetes insipidus. In patients with nephrogenic diabetes insipidus resistant to AVP, calcium fractional excretion did not change significantly after injection 0.48–0.68%, P = NS. In normal subjects undergoing oral water load test, calcium fractional excretion increased significantly from 1.02% to 2.54% P < 0.05. Patients affected by SIADH had a high calcium fractional excretion at baseline that remained stable during test from 3.30% to 3.33% P = NS, possibly resulting from a reduced calcium absorption in renal proximal tubule. In both groups, there was a significant correlation between urine output and calcium renal excretion. In humans, dDAVP decreases calcium fractional excretion in the short term. Conversely, water intake, which lowers AVP concentration, increases calcium fractional excretion. The correlation between urine output and calcium excretion suggests that AVP-related antidiuresis increases calcium reabsorption in collecting ducts.

Keywords : Vasopressin calcium kidney SIADH

Author: Guillaume Hanouna - Jean-Philippe Haymann - Laurent Baud - Letavernier Emmanuel -



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