The Urea–Creatinine Ratio as Marker of Catabolism Is Affected by Continuous Renal Replacement Therapy

<b>Background:</b> An elevated urea–creatinine ratio (UCR) is used as a surrogate for catabolism and elevated protein metabolism in critically ill patients. This study investigated the effect of continuous renal replacement therapy (CRRT) on UCR. <b>Methods:</b> In this retro...

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Main Authors: Andreas Markl-Le Levé, Petra Hillinger, Simon Woyke, Marco Ronzani, Stefan Schmid, Janett Kreutziger, Christopher Rugg
Format: Article
Language:English
Published: MDPI AG 2025-06-01
Series:Diagnostics
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Online Access:https://www.mdpi.com/2075-4418/15/11/1408
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Summary:<b>Background:</b> An elevated urea–creatinine ratio (UCR) is used as a surrogate for catabolism and elevated protein metabolism in critically ill patients. This study investigated the effect of continuous renal replacement therapy (CRRT) on UCR. <b>Methods:</b> In this retrospective single-centre study, ICU patients from 2011 to 2022 with an ICU stay >2 days before CRRT and a CRRT duration of ≥4 days were included. Patients were grouped by UCR at CRRT initiation into high (UCR ≥ 75 mg/dL:mg/dL) and low groups and compared to matched controls not requiring CRRT. Propensity score matching considered age, sex, bodyweight, SAPS3, SOFA score, and UCR values on baseline and pre-baseline days. <b>Results:</b> In the high UCR group, UCR significantly decreased after CRRT initiation, reaching a significant difference from controls on day 2 (85.0 [IQR: 69.5–96.4] vs. 94.4 [IQR: 83.0–115.2]; <i>p</i> = 0.036) and falling below the threshold of 75 by day 3. In the low group, UCR increased post-CRRT initiation, but was less pronounced than in controls, with significant differences on day 1 (44.0 [IQR: 34.2–59.8] vs. 40.6 [IQR: 32.1–52.5]; <i>p</i> = 0.024). <b>Conclusions:</b> CRRT significantly affects UCR in critically ill patients, showing a marked decrease when compared to matched controls.
ISSN:2075-4418