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The meaning of the blood urea nitrogen/creatinine ratio in acute kidney injury.

ABSTRACT: Background:A blood urea nitrogen (BUN)/creatinine ratio (BCR) >20 (0.081 in international unit) is used to distinguish pre-renal azotemia (PRA) and acute tubular necrosis (ATN). However, there is little evidence that BCR can distinguish between these two conditions and/or is clinically useful. Methods:We conducted a retrospective study using a large hospital database. Patients were divided into three groups: 'low BCR' (if BCR when acute kidney injury (AKI) developed was ?20), 'high BCR' (if BCR when AKI developed was >20) and 'no AKI' if patients did not satisfy any of the Risk, Injury, Failure, Loss and End-stage kidney disease criteria for AKI during hospitalization. Results:Among 20 126 study patients, 3641 (18.1%) had AKI. Among these patients, 1704 (46.8%) had a BCR <20 at AKI diagnosis ('low BCR') and 1937 (53.2%) had a BCR >20 ('high BCR'). The average BCR for the two groups was 15.8 versus 26.1 (P < 0.001). Hospital mortality was significantly less in the 'low-BCR' group (18.4 versus 29.9%, P < 0.001). Multivariable logistic regression analysis for hospital mortality ('no AKI' as a reference) showed that the odds ratio of 'high BCR' (5.73) was higher than that of 'low BCR' (3.32). Conclusions:Approximately half of the patients with AKI have a BCR >20, the traditional threshold of diagnosing PRA. Unlike PRA patients who have a lower mortality than ATN patients, high BCR patients had higher hospital mortality compared with low BCR patients, which was confirmed with multivariable analysis. These findings do not support BCR as a marker of PRA.

SUBMITTER: Uchino S

PROVIDER: S-EPMC5783213 | biostudies-literature | 2012 Apr

REPOSITORIES: biostudies-literature

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The meaning of the blood urea nitrogen/creatinine ratio in acute kidney injury.

Uchino Shigehiko S Bellomo Rinaldo R Goldsmith Donna D

Clinical kidney journal 20120401 2

<h4>Background</h4>A blood urea nitrogen (BUN)/creatinine ratio (BCR) >20 (0.081 in international unit) is used to distinguish pre-renal azotemia (PRA) and acute tubular necrosis (ATN). However, there is little evidence that BCR can distinguish between these two conditions and/or is clinically useful.<h4>Methods</h4>We conducted a retrospective study using a large hospital database. Patients were divided into three groups: 'low BCR' (if BCR when acute kidney injury (AKI) developed was ≤20), 'hig ...[more]

PMID: 29497527

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Project description:The present study aimed to determine the association between the blood urea nitrogen (BUN) and creatinine (Cr) ratio and in-hospital mortality in patients with acute myocardial infarction (AMI). The present retrospective cohort study included adult patients (≥18 years of age) who were admitted to the intensive care unit (ICU) with a primary diagnosis of AMI. Medical records were obtained from the electronic ICU collaborative research database, which includes data from throughout continental USA. Data included demographic characteristics, vital signs, laboratory tests and comorbidities. The clinical endpoint was in-hospital mortality. The Cox proportional hazards model was used to evaluate the prognostic values of the basic BUN/Cr ratio and the Kaplan-Meier method was used to plot survival curves. Subgroup analyses were performed to measure mortality across various subgroups. In total, 5,965 eligible patients were included. In the Cox regression analysis, after being adjusted for age, sex, ethnicity and other confounding factors, the BUN/Cr ratio was found to be a significant risk predictor of in-hospital mortality. There was a non-linear relationship between the BUN/Cr ratio and in-hospital mortality after adjusting for potential confounders. A two-piecewise regression model was used to obtain a threshold inflection point value of 18. Furthermore, after adjusting for additional confounding factors (age, sex, ethnicity, BMI, heart rate, oxygen saturation, platelets, total protein, AMI category, heart failure, history of diabetes, history of hypertension, percutaneous coronary intervention, and administration of norepinephrine, dopamine and epinephrine), the BUN/Cr ratio remained a significant predictor of in-hospital mortality (third vs. first tertile: Hazard ratio, 1.50; 95% CI, 1.08-2.09; P<0.05). The Kaplan-Meier curve for tertiles of the BUN/Cr ratio indicated that in-hospital mortality rates were highest when the BUN/Cr ratio was ≥18.34 after adjustment for age, sex and ethnicity (P<0.05). The present findings demonstrated that a higher BUN/Cr ratio was associated with an increased risk of in-hospital mortality in patients with non-ST-segment elevation myocardial infarction. These results support a revision of how the prognosis of patients with AMI is predicted.

Project description:IntroductionUrea is a toxin present in acute kidney injury (AKI). We hypothesize that reduction in serum urea levels might improve clinical outcomes. We examined the association between the reduction in urea and mortality.MethodsPatients with AKI admitted to the Hospital Civil de Guadalajara were enrolled in this retrospective cohort study. We create 4 groups of urea reduction ratio (UXR) stratified by their decrease in urea from the highest index value in comparison to the value on day 10 (0%, 1-25%, 26-50%, and >50%), or at the time of death or discharge if prior to 10 days. Our primary endpoint was to observe the association between UXR and mortality. Secondary observations included determination of which types of patients achieved a UXR >50%, whether the modality of kidney replacement therapy (KRT) effected changes in UXR, and if serum creatinine (sCr) value changes were similarly associated with patient mortality.ResultsA total of 651 AKI patients were enrolled. The mean age was 54.1 years, and 58.6% were male. AKI 3 was present in 58.5%; the mean admission urea was 154 mg/dL. KRT was started in 32.4%, and 18.9% died. A trend toward decreased risk of death was observed in association with the magnitude of UXR. The best survival (94.3%) was observed in patients with a UXR >50%, and the highest mortality (72.1%) was observed in patients achieving a UXR of 0%. After adjusting for age, sex, diabetes mellitus, CKD, antibiotics, sepsis, hypovolemia, cardio-renal syndrome, shock, and AKI stage, the 10-day mortality was higher in groups that did not achieve a UXR of at least 25% (OR: 1.20). Patients achieving a UXR >50% were most likely initiated on dialysis due to a diagnosis of the uremic syndrome or had a diagnosis of obstructive nephropathy. Percentage change in sCr was also associated with increased mortality risk.ConclusionsIn our retrospective cohort of AKI patients, the percent decrease in UXR from admission was associated with a stratified risk of death. Patients with a UXR >25% had the best associated outcomes. Overall, a greater magnitude in UXR was associated with improved patient survival.

Project description:The diagnosis of acute kidney injury (AKI), which is currently defined as an increase in serum creatinine (Scr) concentration, provides little information on the condition's actual cause. To improve phenotyping of AKI, many urinary biomarkers of tubular injury are being investigated. Because AKI cases are not frequently biopsied, the diagnostic accuracy of concentrations of Scr and urinary biomarkers for histologic acute tubular injury is unknown.Cross-sectional analysis from multicenter prospective cohort.Hospitalized deceased kidney donors on whom kidney biopsies were performed at the time of organ procurement for histologic evaluation.(1) AKI diagnosed by change in Scr concentration during donor hospitalization and (2) concentrations of urinary biomarkers (neutrophil gelatinase-associated lipocalin [NGAL], liver-type fatty acid-binding protein [L-FABP], interleukin 18 [IL-18], and kidney injury molecule 1 [KIM-1]) measured at organ procurement.Histologic acute tubular injury.Of 581 donors, 98 (17%) had mild acute tubular injury and 57 (10%) had severe acute tubular injury. Overall, Scr-based AKI had poor diagnostic performance for identifying histologic acute tubular injury and 49% of donors with severe acute tubular injury did not have AKI. The area under the receiver operating characteristic curve (AUROC) of change in Scr concentration for diagnosing severe acute tubular injury was 0.58 (95% CI, 0.49-0.67) and for any acute tubular injury was 0.52 (95% CI, 0.45-0.58). Compared with Scr concentration, NGAL concentration demonstrated higher AUROC for diagnosing both severe acute tubular injury (0.67; 95% CI, 0.60-0.74; P=0.03) and any acute tubular injury (0.60; 95% CI, 0.55-0.66; P=0.005). In donors who did not have Scr-based AKI, NGAL concentrations were higher with increasing severities of acute tubular injury (subclinical AKI). However, compared with Scr concentration, AUROCs for acute tubular injury diagnosis were not significantly higher for urinary L-FABP, IL-18, or KIM-1.The spectrum of AKI cause in deceased donors may be different from that of a general hospitalized population.Concentrations of Scr and kidney injury biomarkers (L-FABP, IL-18, and KIM-1) lack accuracy for diagnosing acute tubular injury in hospitalized deceased donors. Although urinary NGAL concentration had slightly higher discrimination for acute tubular injury than did Scr concentration, its overall AUROC was still modest.

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The meaning of the blood urea nitrogen/creatinine ratio in acute kidney injury.

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The meaning of the blood urea nitrogen/creatinine ratio in acute kidney injury.

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