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Evidence for increased postprandial distal nephron calcium delivery in hypercalciuric stone-forming patients
- Source :
- American Journal of Physiology-Renal Physiology. 295:F1286-F1294
- Publication Year :
- 2008
- Publisher :
- American Physiological Society, 2008.
-
Abstract
- A main mechanism of idiopathic hypercalciuria (IH) in calcium stone-forming patients (IHSF) is postprandial reduction of renal tubule calcium reabsorption that cannot be explained by selective reduction of serum parathyroid hormone levels; the nephron site(s) responsible are not as yet defined. Using fourteen 1-h measurements of the clearances of sodium, calcium, and endogenous lithium during a three-meal day in the University of Chicago General Clinical Research Center, we found reduced postprandial proximal tubule reabsorption of sodium and calcium in IHSF vs. normal subjects. The increased distal sodium delivery is matched by increased distal reabsorption so that urine sodium excretions do not differ, but distal calcium reabsorption does not increase enough to match increased calcium delivery, so hypercalciuria results. In fact, urine calcium excretion and overall renal fractional calcium reabsorption both are high in IHSF vs. normal when adjusted for distal calcium delivery, strongly suggesting a distal as well as proximal reduction of calcium reabsorption. The combination of reduced proximal tubule and distal nephron calcium reabsorption in IHSF is a new finding and indicates that IH involves a complex, presumably genetic, variation of nephron function. The increased calcium delivery into the later nephron may play a role in stone formation via deposition of papillary interstitial apatite plaque.
- Subjects :
- Adult
Male
medicine.medical_specialty
Physiology
Hypercalciuria
Parathyroid hormone
chemistry.chemical_element
Blood Pressure
Nephron
Lithium
Calcium
Renal chloride reabsorption
Kidney Tubules, Proximal
Kidney Calculi
Internal medicine
medicine
Humans
Kidney
Renal sodium reabsorption
Translational Physiology
Chemistry
Reabsorption
Sodium
Nephrons
Middle Aged
Postprandial Period
medicine.disease
Endocrinology
medicine.anatomical_structure
Creatinine
Potassium
Female
Subjects
Details
- ISSN :
- 15221466 and 1931857X
- Volume :
- 295
- Database :
- OpenAIRE
- Journal :
- American Journal of Physiology-Renal Physiology
- Accession number :
- edsair.doi.dedup.....d7c7d2a7b502a361fc9257d4359471fb