Aditya Verma1, Dr Camila Eleuterio Rodrigues2, Dr Amy Au1,3, Dr Jonathan Erlich1,3, Prof Zoltan Endre1,3
1School of Clinical Medicine, University Of New South Wales (UNSW), Kensington, Sydney, Australia, 2Hospital das Clinicas da FMUSP, Sao Paulo, Brazil, 3Department of Nephrology, Prince of Wales Hospital, Randwick, Sydney , Australia
Biography:
I commenced studying a Bachelor of Medical Studies/Doctor of Medicine degree in 2022 at UNSW. I am currently, a fourth year medical student at UNSW completing my Honours research project in Nephrology (AKI). I have completed two pre-clinical years (year one and two) and one semi-clinical year (year three). I have participated in various extra-curricular activities including the academics committee and medical student aid project. I am interested in researching and learning more about nephrology.
Aim:
To evaluate urinary biomarkers in detecting cardiac surgery-associated acute kidney injury (CSA-AKI).
Background:
CSA-AKI increases mortality risk and in survivors, increases chronic kidney disease and dialysis risk. AKI is diagnosed using the KDIGO criteria which utilises serum creatinine (SCr) and/or urine output measurements. Given the limitations of SCr in AKI diagnosis, urinary biomarkers of kidney injury – Kidney Injury Molecule-1 (KIM-1) and Neutrophil Gelatinase-Associated Lipocalin (NGAL) – are increasingly being investigated.
Methods:
68 adults undergoing cardiac bypass surgery had blood and urine samples collected at preoperative (baseline) and postoperatively at 0- (within 12 hours), 1-, 2- and 3-days post-surgery. Urinary biomarkers were measured using a solid-phase sandwich ELISA and normalised to urinary creatinine (UCr).
Results:
KDIGO-defined AKI incidence was 45.6% (n = 31/68), mostly occurring at Day 1 post-surgery (30.9%).
Within 12 hours post-surgery, median KIM-1/UCr [IQR] increased 1.83-fold [1.28-2.65] from baseline (p=0.06). This was followed by a further 2.83-fold [1.46-4.50] increase by Day 1 post-surgery (p<0.01). In contrast, cardiopulmonary bypass-induced haemodilution resulted in SCr initially declining by 11.1% [4.4-17.5] within 12 hours (p<0.01) before increasing by 7.5% [1.5-13.8] from 12 hours post-surgery to Day 1 (p<0.01). There was not a significant postoperative rise in NGAL/UCr from baseline until Day 2 post-surgery where NGAL/UCr increased 3.66-fold [1.00-7.65] (p<0.01).
NGAL/UCr was higher in AKI patients compared to non-AKI patients within 12 hours post-surgery (2.56 [1.08-9.10] vs 1.07 [0.70-2.06] µg/mmol UCr; p=0.12) and at Day 1 post-surgery (2.69 [1.09-7.24] vs 1.58 [0.96-2.15] µg/mmol UCr; p=0.11).
Conclusions:
KIM-1 is an earlier biomarker of kidney injury as compared to NGAL and SCr following cardiac surgery.
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