Blood Urea Nitrogen

BackgroundBlood urea nitrogen (BUN) is one of the substances that affects the calculated serum osmolality (cSosm). A previous study demonstrated that BUN and cSosm were independently associated with the development of chronic kidney disease (CKD) in patients with preserved kidney function. In advanced CKD stages, there is a concomitant increase in cSosm and BUN levels. However, it remains unclear whether BUN or cSosm levels are related to renal outcomes in patients with moderate to severe kidney dysfunction. The aim of this study was to clarify whether the BUN or cSosm level is associated with kidney disease progression in patients with advanced CKD.MethodsIn this prospective study, we enrolled 459 patients with CKD (stages 3-5). The composite renal endpoint was end-stage renal disease (ESRD) or death, and ESRD alone was added as an alternative outcome. A Cox proportional hazards model was utilized to determine the risk factors for a poor renal outcome. We adjusted for covariates including estimated glomerular filtration rate (eGFR). The cSosm (mOsm/kg) was calculated using the following formula: (2 × sodium) + (BUN/2.8) + (glucose/18).ResultsDuring a median follow-up of 25.8 months, the renal endpoint was observed in 210 patients. Multivariable Cox analysis determined the hazard ratio (HR) [95% confidence interval (CI)] for the composite renal outcome in the second, third, and fourth BUN quartiles were 1.36 (0.72-2.58), 1.87 (0.95-3.66), and 2.66 (1.23-5.76) (P for trend ConclusionsHigher BUN levels, but not cSosm levels, were associated with adverse renal outcomes independent of the eGFR, suggesting that BUN may be a useful marker for predicting kidney disease progression.

PurposeBlood urea nitrogen (BUN) was reported to be associated with mortality in heart failure patients. We aimed to evaluate admission BUN concentration in a heterogeneous critically ill patient collective admitted to an intensive care unit (ICU) for prognostic relevance.MethodsA total of 4176 medical patients (67±13 years) admitted to a German ICU between 2004 and 2009 were included. Follow-up of patients was performed retrospectively between May 2013 and November 2013. Association of admission BUN and both intra-hospital and long-term mortality were investigated by Cox regression. An optimal cut-off was calculated by means of the Youden-Index.ResultsPatients with higher admission BUN concentration were older, clinically sicker and had more pronounced laboratory signs of multi-organ failure including kidney failure. Admission BUN was associated with adverse long-term mortality (HR 1.013; 95%CI 1.012-1.014; p28 mg/dL to case-controls ≤ 28mg/dL corrected for APACHE2 scores: BUN above 28 mg/dL remained associated with adverse outcome in a paired analysis with the difference being 5.85% (95%CI 1.23-10.47%; p = 0.02).ConclusionsHigh BUN concentration at admission was robustly associated with adverse outcome in critically ill patients admitted to an ICU, even after correction for co-founders including renal failure. BUN might constitute an independent, easily available and important parameter for risk stratification in the critically ill.

Background and Aims. This study evaluated the prognostic accuracy of BUN for severe acute pancreatitis (SAP) and in-hospital mortality (IHM) in terms of the best timing for BUN measurement and the optimal BUN cutoff points. Methods. BUN determinants at the time of admission and 24 hrs after hospital admission were recorded and analyzed statistically. The ability of BUN in predicting the SAP and the occurrence of IHM were assessed using the area under the receiver-operating characteristic (ROC) curve. Results. For SAP, AUC of BUN at admission and 24 hrs after hospital admission was 0.75 and 0.80, respectively. For IHM in acute pancreatitis, it was 0.86 at admission and 0.84 after 24 hrs of hospital admission, respectively. The optimal cutoff point of BUN 24 hrs after hospital admission for SAP and at admission for IHM was 8.3 mmol/L and 13.3 mmol/L, respectively. Conclusion. BUN determination after 24 hrs of hospital admission has high accuracy for prediction of SAP while BUN at initial admission has high accuracy for prediction of IHM.

AimsTo synthesize the existing evidence on the association of BCR with clinical outcomes in patients with heart failure.MethodsA comprehensive and systematic search of observational studies was conducted across five major databases-PubMed, Embase, Scopus, Web of Science, and Google Scholar-covering all records up to February 2024. The primary outcomes of interest included mortality, rehospitalization, cardiovascular events, and renal complications. To evaluate the methodological quality, the Newcastle-Ottawa scale was applied, allowing for the structured assessment of bias across the selection, comparability, and outcome domains. Additionally, the certainty of the evidence was appraised using the GRADE framework.ResultsTwenty studies including 21 397 HF patients were analyzed. For ≥ 1-year mortality (11 661 participants, 11 studies), hazard ratios ranged from 1.30 to 2.19, with the strongest association in HF with preserved ejection fraction (HR: 3.28, 95% CI: 2.00-5.38) with very low certainty. It also correlated with worse NYHA class IV versus II (MD: 12.03, 95% CI: 10.54-13.52) and increased risk of 1-month major adverse cardiovascular events (OR: 2.47, 95% CI: 1.01-6.01), both with very low certainty. Most included cohort studies were rated as low risk of bias, with only two studies at moderate risk and one study at high risk.ConclusionElevated BCR is associated with adverse outcomes in patients with heart failure. However, its discriminative performance appears limited, and its incremental value over established biomarkers such as NT-proBNP remains unclear. Further prospective studies are required to determine its clinical utility.