David A Bushinsky1, Kevin K Frick, Keith Nehrke. 1. Division of Nephrology, Department of Medicine, University of Rochester School of Medicine, Rochester, New York 14642, USA. David_Bushinsky@urmc.rochester.edu
Abstract
PURPOSE OF REVIEW: We will describe the pathophysiology of hypercalciuria and the mechanism of the resultant stone formation in a rat model and draw parallels to human hypercalciuria and stone formation. RECENT FINDINGS: Through inbreeding we have established a strain of rats that excrete 8-10 times more urinary calcium than control rats. These genetic hypercalciuric rats absorb more dietary calcium at lower 1,25-dihydroxyvitamin D3 levels. Elevated urinary calcium excretion on a low-calcium diet indicated a defect in renal calcium reabsorption and/or an increase in bone resorption. Bone from hypercalciuric rats released more calcium when exposed to 1,25-dihydroxyvitamin D3. Bisphosphonate significantly reduced urinary calcium excretion in rats fed a low-calcium diet. Clearance studies showed a primary defect in renal calcium reabsorption. The intestine, bone and kidneys of the hypercalciuric rats had increased numbers of vitamin D receptors. When hydroxyproline is added to their diet they form calcium oxalate stones, the most common stone type in humans. Increased numbers of vitamin D receptors may cause hypercalciuria in these rats and humans. SUMMARY: Understanding the mechanism of hypercalciuria and stone formation in this animal model will help clinicians devise effective treatment strategies for preventing recurrent stone formation in humans.
PURPOSE OF REVIEW: We will describe the pathophysiology of hypercalciuria and the mechanism of the resultant stone formation in a rat model and draw parallels to humanhypercalciuria and stone formation. RECENT FINDINGS: Through inbreeding we have established a strain of rats that excrete 8-10 times more urinary calcium than control rats. These genetic hypercalciuric rats absorb more dietary calcium at lower 1,25-dihydroxyvitamin D3 levels. Elevated urinary calcium excretion on a low-calcium diet indicated a defect in renal calcium reabsorption and/or an increase in bone resorption. Bone from hypercalciuric rats released more calcium when exposed to 1,25-dihydroxyvitamin D3. Bisphosphonate significantly reduced urinary calcium excretion in rats fed a low-calcium diet. Clearance studies showed a primary defect in renal calcium reabsorption. The intestine, bone and kidneys of the hypercalciuric rats had increased numbers of vitamin D receptors. When hydroxyproline is added to their diet they form calcium oxalate stones, the most common stone type in humans. Increased numbers of vitamin D receptors may cause hypercalciuria in these rats and humans. SUMMARY: Understanding the mechanism of hypercalciuria and stone formation in this animal model will help clinicians devise effective treatment strategies for preventing recurrent stone formation in humans.
Authors: Nancy S Krieger; John R Asplin; Ignacio Granja; Felix M Ramos; Courtney Flotteron; Luojing Chen; Tong Tong Wu; Marc D Grynpas; David A Bushinsky Journal: J Am Soc Nephrol Date: 2019-05-17 Impact factor: 10.121
Authors: Saeed R Khan; Margaret S Pearle; William G Robertson; Giovanni Gambaro; Benjamin K Canales; Steeve Doizi; Olivier Traxer; Hans-Göran Tiselius Journal: Nat Rev Dis Primers Date: 2016-02-25 Impact factor: 52.329