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After PnL, urine from the nephrostomy tube and externalized ureteral stent were collected over 12 hours and combined to represent the affected/operated kidney. simultaneously, the Foley bladder specimen was collected to represent the contralateral mate kidney. Abbreviation: PnL, percutaneous nephrolithotomy.
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Objectives
Many patients present with bilateral stones. There is a unique group of patients, however, that presents with stones exclusively on one side. We hypothesize that in such situations, 24-hour urine collections may not reveal specific defects on the affected stone-bearing kidney. We therefore evaluated selective 12-hour urine collections af...
Context in source publication
Context 1
... comple- tion of PNL a nephrostomy tube (16 F Foley) was placed in the renal pelvis. The nephrostomy tube, externalized retrograde ureteral exchange catheter in the ipsilateral ureter, and Foley catheter draining the bladder were placed to gravity drainage ( Figure 1). The Foley bladder collection represented urine from the untreated mate kidney. ...
Citations
... Patients with unilateral stones demonstrated lowered urine excretion of uric acid, sodium, chloride, calcium, and total osmoles from the treated kidney compared to patients with bilateral nephrolithiasis. [10] While insightful, this study was confounded by the presence of a nephrostomy tube, which may have changed tubular function, and direct drainage from the bladder by a foley catheter. Drainage of urine through a unilateral tube (i.e., nephrostomy tube) or by placing an external ureteral stent (i.e., without an obstructing balloon at the ureteropelvic junction) limits the differentiation between urine produced by each kidney, because urine invariably drains down the ureter and mixes in the bladder. ...
... Of concern is that using a nephrostomy tube to collect the urine from the stone side might have altered renal function and urinary electrolyte excretion in the stone-forming side in addition to potentially adding another confounder, that of bacterial infestation which is common when a nephrostomy tube is in place. [10,11] Also, the nephrostomy tube would not drain all the urine from the affected kidney; also, some urine from the stone bearing kidney would still reach the bladder and be mixed with the urine from the unaffected kidney. ...
INTRODUCTION: Twenty-four-hour urine testing is performed to identify urine electrolyte abnormalities that are associated with kidney stone formation. This analysis pools urine from the two kidneys even though in many patients, stones affect only one renal unit. Our goal was to determine if there were significant differences in urine electrolytes between the stone-bearing and the stone-free kidney.
METHODS: Fourteen adult patients with unilateral nephrolithiasis scheduled for ureteroscopy or percutaneous nephrolithotomy were enrolled. Following Foley catheter drainage of the bladder, a ureteral access sheath (UAS) was passed into the stone-bearing kidney. Urine was collected simultaneously from the UAS (intervention) and from the Foley catheter (control) for 10-15 minutes. Samples were analyzed for urine stone risk factors. Pairwise comparison was made between the two kidneys using both raw concentration values and concentration values corrected for creatinine. The amount of urine collected determined the type of analysis performed. In those patients where at least 6ml of urine was collected, the samples were split into two samples, one for the addition of thymol and the other for the addition of hydrochloric acid (HCl).
RESULTS: Among the 14 patients, there were 11 complete thymol samples and 5 complete HCl samples. There were differences at the individual level between the kidneys. In the HCl samples, all patients had unilateral metabolic differences related to stone formation: higher urinary calcium in three, higher urinary oxalate in one and lower urinary citrate in one patient.
CONCLUSIONS: In most patients, there were urinary metabolite differences between the renal units, most notably in urinary calcium concentration.
