Maciel AT. Giving urine biochemistry a second chance in acute kidney injury monitoring. World J Crit Care Med 2025; 14(4): 109194 [DOI: 10.5492/wjccm.v14.i4.109194]
Corresponding Author of This Article
Alexandre Toledo Maciel, Head, MD, Department of Research, Imed Group, Hospital São Camilo Pompéia Adult ICU, Pompeia Avenue 1178 4th floor, São Paulo 05022-001, Brazil. alexandre.toledo@imedgroup.com.br
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Critical Care Medicine
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Opinion Review
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This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/
Dec 9, 2025 (publication date) through Dec 9, 2025
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Publication Name
World Journal of Critical Care Medicine
ISSN
2220-3141
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Baishideng Publishing Group Inc, 7041 Koll Center Parkway, Suite 160, Pleasanton, CA 94566, USA
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Maciel AT. Giving urine biochemistry a second chance in acute kidney injury monitoring. World J Crit Care Med 2025; 14(4): 109194 [DOI: 10.5492/wjccm.v14.i4.109194]
World J Crit Care Med. Dec 9, 2025; 14(4): 109194 Published online Dec 9, 2025. doi: 10.5492/wjccm.v14.i4.109194
Giving urine biochemistry a second chance in acute kidney injury monitoring
Alexandre Toledo Maciel
Alexandre Toledo Maciel, Department of Research, Imed Group, Hospital São Camilo Pompéia Adult ICU, São Paulo 05022-001, Brazil
Author contributions: Maciel AT conceived the review, collected the clinical and laboratory data, and wrote the paper, producing this manuscript on behalf of the Imed Group of Investigators.
Conflict-of-interest statement: The author declares no conflicts of interest.
Open Access: This article is an open-access article that was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution NonCommercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: https://creativecommons.org/Licenses/by-nc/4.0/
Corresponding author: Alexandre Toledo Maciel, Head, MD, Department of Research, Imed Group, Hospital São Camilo Pompéia Adult ICU, Pompeia Avenue 1178 4th floor, São Paulo 05022-001, Brazil. alexandre.toledo@imedgroup.com.br
Received: May 6, 2025 Revised: June 4, 2025 Accepted: July 22, 2025 Published online: December 9, 2025 Processing time: 210 Days and 22.9 Hours
Abstract
Most studies assessing urine biochemistry for acute kidney injury (AKI) monitoring rely on paradigms from the 1970s. It was proposed that a single measurement of urinary parameters in the presence of increased serum creatinine (sCr) could help understand AKI pathophysiology and predict its duration. However, those studies produced variable and controversial results. Recently, an alternative “urine biochemical approach” has been proposed. In contrast with the traditional approach, it includes sequential urine electrolyte assessment, evaluation before AKI diagnosis, and interpretation of avid sodium retention as a marker of renal microcirculatory stress instead of low renal perfusion. This review highlights the rationale of this alternative approach, which is focused on early urinary biochemical changes that precede increases in sCr as well as signs of renal recovery before decreases in sCr. The relevance of urine composition in conjunction with urine volume for a proper evaluation of renal function is emphasized. This new approach aims to enhance the utility of urinary biochemical parameters in AKI monitoring, particularly in patients who are critically ill.
Core Tip: The utility of urine biochemistry assessment for acute kidney injury (AKI) monitoring was proposed 50 years ago, being theoretically capable of defining AKI pathophysiology and distinguishing functional (“pre-renal”) and structural (“renal”) impairments. However, the actual usefulness of urine biochemistry was never confirmed due to variable and controversial results among studies. In this review, alternative considerations for when to assess urine electrolytes and how to interpret their values for renal function monitoring are proposed.
