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Kidney Week

Abstract: SA-PO132

Cystatin C as a Diagnostic Marker for a Postoperative Urine Leak

Session Information

Category: Acute Kidney Injury

  • 102 AKI: Clinical, Outcomes, and Trials

Authors

  • Maheshwari, Rahul, Icahn School of Medicine at Mount Sinai, New York, New York, United States
  • Kott, Jeffrey, Icahn School of Medicine at Mount Sinai, New York, New York, United States
  • Koncicki, Holly M., Icahn School of Medicine at Mount Sinai, New York, New York, United States
Introduction

Evaluating kidney function after urologic procedures can be challenging in the presence of complications such as urine leaks. This case report illustrates a scenario where serum creatinine provided misleading Glomerular Filtration Rate (GFR) estimations, prompting the use of cystatin C for diagnostic accuracy.

Case Description

A 67-year-old male with a history of prostate cancer underwent uneventful robotic assisted laparoscopic prostatectomy. Postoperatively, serum creatinine rapidly increased from a baseline of 0.9 mg/dL. On postoperative day (POD) 1, significant output from a Jackson-Pratt (JP) drain indicated possible urine leak. However, a CT scan on POD 2 did not show obstruction or leak. Due to ongoing suspicion, nephrology consultation recommended obtainng daily cystatin C, hypothesizing that elevated serum creatinine mirrored urine resorption rather than a GFR decline. On POD 5, discrepant serum creatinine and cystatin C values (10.95 mg/dL, 1.5 mg/L respectively) along with a JP drain fluid creatinine of >40 mg/dL led to the placement of nephrostomy tubes. Post-procedure, serum creatinine and cystatin C levels normalized and JP output decreased.

Discussion

This case highlights the use of cystatin C in diagnosing postoperative urine leaks and the limitations of using serum creatinine as the sole kidney function marker after urologic procedures. Despite a non-diagnostic CT scan, the divergent serum creatinine and cystatin C pointed towards a urine leak. The mild cystatin C elevation, which improved post nephrostomy tube placement, suggests some obstructive uropathy or intrinsic kidney injury. Our case aligns with a case by Saro-Nunez et al 2018, where cystatin C was similarly used for eGFR measurements in a urinoma. Cystatin C, correlates with residual kidney function in peritoneal dialysis patients, suggesting minimal transport across the peritoneal membrane. Considering creatinine's absorption in peritoneal and retroperitoneal spaces, cystatin C may offer a more reliable marker. This case highlights cystatin C's potential utility in urologic surgery complications like urine leaks, despite its rare use in acute kidney injury.