Utility of Cystatin C in the Setting of Urinoma

Elevated serum creatinine levels are a common finding in patients with urinoma (i.e. presence of urine outside of the urinary tract). Therefore, in the clinical circumstance of an urinoma, utilizing a creatinine-based estimated GFR (eGFR) to determine renal function is unreliable, as it fails to distinguish true renal failure from pseudorenal failure in patients with a urine leakage. Cystatin C, a 13 kDA molecular mass protein ubiquitously expressed by nucleated cells, offers superior accuracy in the setting of an urinoma, since unlike creatinine, it is essentially absent in excreted urine and poorly reabsorbed from the peritoneum and retroperitoneal space. We present the first case report to demonstrate the utility of cystatin C in an adult patient with native kidney function that experienced significant retro-peritoneal bladder leakage. Our results demonstrate that cystatin C may be a more accurate measurement of GFR than the commonly used creatinine in the setting of an urinoma. In order to achieve an accurate estimated GFR in the setting of a urinoma, physicians should consider the use of Cystatin C, which is less vulnerable to inaccurate interpretation.