Urinary Biomarkers for The Prediction of Reversibility in Acute-on-Chronic Renal Failure

Abstract

BACKGROUND: There is no reliable clinical test to predict the reversibility of acute-on-chronic renal failure. We study whether urinary biomarkers could be used as a noninvasive prognostic marker in patients with acute-on-chronic renal failure. METHODS: We studied 39 adult patients with pre-existing chronic renal impairment presenting to us with acute-on-chronic renal failure. Urinary neutrophil gelatinase-associated lipocalin (NGAL) level was measured. The mRNA of kidney injury molecule-1 (KIM-1), interleukin-18 (IL-18), alpha-1-microglobulin ( α 1M), sodium/hydrogen exchanger-3 (NHE3), beta-2 microglobulin ( β 2M), and N-acetyl- β -D-glucosaminidase (NAG) in urinary sediment were quantified. RESULTS: Urinary NGAL level significantly correlated with the serum creatinine at presentation ( r = 0.762, p < 0.0001) but not baseline serum creatinine. Urinary sediment β 2M expression significantly correlated with baseline glomerular filtration rate (GFR) ( r = –0.400, p = 0.012). Urinary α 1M and NHE3 expressions were significantly higher in ischemic acute tubular necrosis than other causes of acute kidney injury ( p < 0.0001 and p = 0.006, respectively). Urinary α 1M expression significantly correlated with the degree of improvement in renal function ( r = 0.387, p = 0.026), as well as the estimated GFR 6 months later ( r = 0.386, p = 0.027). CONCLUSION: In patients with acute-on-chronic renal failure, urinary NGAL level correlates with the severity of renal failure, while urinary α 1M expression correlates with the degree of renal function recovery. Quantification of urinary α 1M mRNA may be developed as an non-invasive tool for risk stratification of this group of patients.