Utility of urine microscopy and urinary biomarkers in early detection of acute kidney injury in a cohort of patients admitted with a clinical diagnosis of acute decompensated heart failure

Punit Goyal, Rajesh Verma, Shiv Shankar Sharma, Vivek C Ganiger, Prachi Goyal


Background: Acute Kidney Injury (AKI) is a common clinical syndrome in hospitalized patients, especially in intensive care units and is a strong risk factor for development of Chronic Kidney Disease (CKD). AKI is a common association in patients admitted for Acute Decompensated Heart Failure (ADHF). AKI is an independent predictor of mortality and poor long term outcome in patients presenting with ADHF. Presently available diagnostic tests in particular serum creatinine, are not helpful in early detection of AKI. Thus a diagnostic tool which can help in early detection of AKI, differentiate various types of AKI, grade the severity of AKI, and suggest appropriate management strategy in patients with
ADHF, is need of the hour.
Objectives: To analyze role of urine microscopy & urinary biomarkers (N-Acetyl-beta-DGlucosaminidase, NAG; and Kidney injury molecule type 1, KIM-1) in early detection of AKI and its differentiation into pre-renal and ATN variety in patients admitted with a clinical diagnosis of ADHF.
Materials and Methods: 40 patients of ADHF with AKI, along with 25 controls (ADHF without AKI) were studied from January 2019 to December 2019. Urine microscopy with sediment analysis and measurement of urinary biomarkers were done.
Results: Urine microscopy helped in differentiation of pre-renal AKI from ATN. The role of urinary sediment examination in risk stratification of AKI did not show a significant correlation between presence of granular casts and three stages of AKI with a P value of 0.561. Levels of urinary KIM-1 and NAG were
higher in ADHF with AKI cases as compared to controls with a significant P value of <0.0001 for KIM-1 and 0.003 for NAG. Levels were also higher in cases whose samples were taken within 24 hours of symptom onset of AKI, with a highly significant p value of <0.0001 and 0.001 for KIM-1 and NAG respectively.
However urinary biomarker levels did not help in risk stratification of the patients. The correlation of three stages of AKI with urinary levels of KIM-1 and NAG had a P Value of 0.74 and 0.504 respectively. ROC of NAG and KIM-1 were plotted. AUC calculated for KIM-1 was 0.998, for NAG was 0.718 and for the combination was 0.724. There was a significant difference between AUC of KIM-1 and NAG with a p value of <0.001. There was also a significant difference between AUC of KIM-1 and combination of KIM-1 and NAG with a p value <0.001.
Conclusions: Urine microscopy is a readily available & inexpensive tool which can help in differential diagnosis of AKI into pre-renal AKI and ATN variety; so that correct therapy can be initiated in time but may not always help to risk stratify patients. The two urinary biomarkers analyzed (KIM-1 and NAG) are useful in early detection of AKI in ADHF patients, however their combination did not have any added advantage of early diagnosis.

Keywords: Acute Kidney Injury (AKI).

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