RESUMO
OBJECTIVE: Urinary tract infection (UTI) is a common cause of morbidity and hospitalisation in the population worldwide. Upper UTI is indolent and causes subclinical acute kidney injury (AKI) resulting in preventable cause of scarring of renal parenchyma. We explored urinary and serum levels of kidney injury molecule-1 (KIM-1), haematological parameters and quantitative urine microscopy parameters to predict kidney injury. METHODS: Neutrophil-lymphocyte ratio (NLR) is obtained by dividing absolute neutrophil count with absolute lymphocyte count. Quantitative urine sediment microscopy was performed and correlated with clinical, biochemical and haematological findings to predict AKI in patients with UTI. Quantitative ELISA was performed for serum and urine levels of KIM-1. Seventy two adult patients with UTI were enrolled, 45 of whom had AKI while 27 were in the non-AKI group. RESULTS: NLR (p=0.005) and renal tubular epithelial cell-granular cast score in quantitative urine microscopy (p=0.008) are strong predictors of AKI in patients with UTI while rest of quantitative urine microscopy parameters and serum and urinary levels of KIM-1 molecule were not found to be useful in prediction of AKI. CONCLUSION: NLR in haemogram is a novel and useful biomarker for predicting AKI in patients with UTI.
RESUMO
BACKGROUND: Febrile urinary tract infection (fUTI) can be associated with acute kidney injury (AKI). We aimed to study the risk factors for AKI, its pathophysiological categories, and the role of urinary neutrophil gelatinase-associated lipocalin (uNGAL) in differentiating these categories in patients hospitalized with fUTI. MATERIALS AND METHODS: We prospectively studied patients with fUTI admitted to the Department of Medicine of a tertiary care hospital in southern India from January 2017 to December 2018. Clinical evaluation, renal imaging, and estimation of fractional excretion of sodium (FeNa) and uNGAL were done at baseline. AKI was defined as ≥ 0.3 mg/dL rise in serum creatinine (SCr) within 48 hours during hospital stay (KDIGO criterion) or discharge SCr value 0.5 mg/dL or less compared to peak SCr after admission. RESULTS: We studied 100 patients. Their mean age was 52 (± 14) years; 45 were men. In all, 52 had AKI: pre-renal in 11 (21%), intrinsic renal in 24 (47%), post-renal in 16 (31%), and missing data 1 patient. uNGAL levels were significantly higher in the AKI group compared to the no-AKI group (median [IQR] 91.1 [13.2 - 188] vs. 264.9 [115.2 - 355.2] ng/mL; p < 0.001). On multivariable analysis, male sex (adjusted odds ratio, aOR [95% CI] 2.8 [1.09 - 7.14]), hypertension (4.12 [1.24 - 13.7]) and hydroureteronephrosis (7.82 [1.55 - 39.4]) were independently associated with AKI. There was an increasing trend of uNGAL across the three categories of AKI (pre-renal 106.1 [14.6 - 261.7] ng/mL, intrinsic renal 210.8 [8.5 - 353.8] ng/mL, and post-renal 335.5 [269.2 - 692.8] ng/mL; p = 0.001). Patients with pre-renal AKI had significantly lower levels of uNGAL compared to the other two categories combined (106.1 [14.6 - 261.7] vs. 284.6 [179 - 434.4] ng/mL; p = 0.016). CONCLUSION: Hospitalized fUTI patients should be evaluated for AKI, and obstructive uropathy should be ruled out in those with AKI. uNGAL levels may help in differentiating the pre-renal type of AKI from the other two categories.
