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Bicarbonate re-absorption in renal stone patients with acidification defects
Scandinavian Journal of Urology and Nephrology
|January 1, 1976
Summary
Renal stone formers often show impaired kidney acidification. This study found increased bicarbonate wasting in many patients, potentially increasing the risk of calcium-phosphate kidney stones.
Area of Science:
- Nephrology
- Renal Physiology
- Urolithiasis Research
Background:
- Renal stone formation is frequently associated with pathological renal responses to acid loading.
- Impaired kidney acidification capacity is a suspected underlying factor in recurrent renal stone disease.
Purpose of the Study:
- To investigate the impaired acidification capacity in renal stone formers.
- To identify specific defects in bicarbonate handling in patients with a history of kidney stones.
Main Methods:
- Eight renal stone formers underwent bicarbonate loading tests.
- Assessment of bicarbonate threshold and maximal tubular reabsorption of bicarbonate (Tm) was performed.
- Fractionated bicarbonate excretion was analyzed at normal plasma bicarbonate levels.
Main Results:
- Five patients with suspected proximal acidification defects and two with distal defects exhibited a low bicarbonate threshold and increased fractional bicarbonate excretion.
- Four patients with suspected proximal defects had a low maximal reabsorption of bicarbonate (Tm).
- Three patients did not reach a Tm, indicating significant bicarbonate wastage.
Conclusions:
- Increased bicarbonate wastage from the kidneys is a key finding in a subset of renal stone formers.
- Consistently alkaline urine, resulting from proximal acidification defects, may elevate the risk of calcium-phosphate kidney stone precipitation.