The relative contribution of urine extravasation to elevation of plasma creatinine levels in acute unilateral ureteral obstruction

Abstract

Introduction: Rising levels of plasma creatinine in the setting of acute unilateral ureteral obstruction (AUUO) often reflects acute renal failure, mandating kidney drainage. We hypothesize that reabsorption of peri-renal urine extravasation (PUE), a common result of UUO, contributes significantly to the elevation in plasma creatinine, rendering the latter an inaccurate benchmark for renal function. We explored this hypothesis in a rat model of AUUO and PUE. Methods: In total, 20 rats were equally divided into 4 groups. Groups 1 and 2 underwent unilateral ligation of the ureter with infiltration of rat's urine (index group) or saline (control) into the peri-renal space. Two additional control groups underwent perirenal injection of either urine or saline without AUUO. Plasma creatinine levels were determined immediately prior to the procedure (T0), and hourly for 3 hours (T1, T2 and T3). Renal histology was investigated after 3 hours. Results: Rats in the index group had a significantly greater increase in plasma creatinine levels over 3 hours compared to all other groups (p < 0.05). At T3, average plasma creatinine levels for the index group increased by 96% (0.49 ± 0.18 mg/dL) compared to 46% (0.23 ± 0.06 mg/dL increase) in the AUUO and saline group, and less than 15% rise in both the non-obstructed control groups. Our study limitations includes lack of spontaneous PUE and intraperitoneal surgical approach. Conclusions: Absorption of peri-renal urine in the presence of AUUO is a significant contributor to rising plasma creatinine levels, beyond those attributable to the obstruction alone, and may overestimate the extent of the true renal functional impairment.

An interesting presentation of invasive bladder carcinoma as pseudo renal failure

“…The probable mechanism for this phenomenon in our case may be a peri-renal urine extravasation from a rupture of the calyceal fornix secondary to high intra-pelvic pressures, resulting in urinary ascites followed by subsequent re-absorption by lymphatic or venous channels. 20 Clinicians should distinguish pseudo renal failure from true renal failure based on laboratory analysis of peritoneal fluid, which has higher levels of urea, creatinine, and potassium than serum. [1][2][3][4][5][6][7][8][9][10] Emergency management of these patients depend on the clinical scenario.…”

Rho Kinase Inhibitor, Fasudil, Attenuates Contrast‐induced Acute Kidney Injury

“…Significant alterations in renal function parameters have been observed after unilateral ligation of the renal vein [25]. At the same time, a more marked increase in plasma creatinine levels has been observed in rats with a unilateral ureteral obstruction [26]. And, unilateral occlusion of the renal artery could also induce renal dysfunction [27].…”

Acute Unilateral Ureteric Obstruction in Young Men With High Serum Creatinine: Is It True or False Renal Impairment?

“…There is a growing evidence from literature that renal impairment in AUUO is due to absorption of obstructed urine with its high creatinine back to systemic circulation. This is considered false renal impairment with normal GFR [9]. In our study, we measured renal function through measurement of eGFR using Tc-99m-DTPA.…”

“…Recently, published animal study proved that in AUUO, back flow of obstructed urine into venous and lymphatic vessels causes elevation of serum creatinine. Accordingly, this rise of serum creatinine is considered a false renal impairment (pseudo renal failure) due to absorption of obstructed urine with its high creatinine levels [9].…”