Differences in quantitative urine composition in stone-forming versus unaffected mate kidneys.

Area of Science:

• Nephrology
• Urology
• Biochemistry

Background:

• Nephrolithiasis (kidney stones) can be unilateral or bilateral.
• Standard 24-hour urine collections may not detect specific defects in unilateral stone disease.
• Percutaneous nephrolithotomy (PNL) is a surgical procedure for kidney stone removal.

Purpose of the Study:

• To evaluate selective 12-hour urine collections after unilateral PNL.
• To determine if there is differential renal excretion in patients with unilateral versus bilateral nephrolithiasis.
• To investigate potential causes of unilateral stone formation.

Main Methods:

• Collected urine from nephrostomy tubes (affected kidney) and Foley catheters (contralateral kidney) post-unilateral PNL.
• Analyzed urine specimens from 31 patients (14 unilateral, 17 bilateral nephrolithiasis).
• Compared urine composition between affected and contralateral kidneys, and between unilateral and bilateral stone groups.

Main Results:

• Treated kidneys in unilateral nephrolithiasis patients showed lower excretion of uric acid, sodium, chloride, calcium, and total osmoles compared to bilateral cases.
• No significant correlation found between stone size or procedure length and post-PNL urine composition.
• Differential renal excretion patterns were observed in unilateral stone formers.

Conclusions:

• Unilateral PNL patients exhibit distinct urine excretion profiles compared to bilateral PNL patients.
• Observed differences may result from surgical insult, the stone disease itself, or contribute to stone pathogenesis.
• 12-hour urine collections after PNL can reveal differential renal excretion relevant to unilateral stone disease.