About Blood Urea Nitrogen (BUN)
Blood Urea Nitrogen (BUN) is a waste product formed in the liver from the breakdown of proteins and is transported to the kidneys for excretion. BUN is a key marker for assessing kidney function as it indicates how well the kidneys are excreting urea. In clinical settings, it is one of the most commonly used biomarkers to assess renal function and hydration status.
Reference Values
Optimal Range
7.0 - 20.0 mg/dL
Women's Optimal Range
7.0 - 20.0 mg/dL
Elite Value
Not specified
Health Implications
{'high': 'Elevated levels may indicate kidney dysfunction or dehydration, and could also result from heart failure or a high-protein diet.', 'low': 'Low levels may be associated with liver disease, malnutrition, or an overhydrated state which can affect kidney function.'}
Symptoms
High
May include fatigue, headaches, swelling, and unusual itching.
Low
Can include dizziness, weakness, confusion, and rapid heartbeat.
Lifestyle Factors
Specimen Type
Testing Methods
Also Known As
Scientific Sources
- an, J., Li, Y., & Yang, L. (2023). Predictive value of blood urea nitrogen in heart failure: a systematic review and meta-analysis. *PubMed*.
- ng, Y., Xu, X., Shi, S., Gao, X., Li, Y., Wu, H., Song, Q., & Zhang, B. (2023). Blood urea nitrogen to creatinine ratio and long-term survival in patients with chronic heart failure. *European Journal of Medical Research*, 28, 343.
- ndo, E., Alberti, P., Mata, R., Gomez, M. J., Vidal, L., Cirera, A., Dopazo, C., Blanco, L., Gomez, C., Caralt, M., Balsells, J., & Charco, R. (2021). Early changes in blood urea nitrogen (BUN) can predict mortality in acute pancreatitis: comparative study between BISAP score, APACHE-II, and other laboratory markers—a prospective observational study. *Canadian Journal of Gastroenterology and Hepatology*.
- n, Q., Zheng, L., Zhou, X., Wu, H., Buys, N., Liu, Z., Sun, J., & Fan, H. (2021). The value of blood urea nitrogen in the prediction of risks of cardiovascular disease in an older population. *Frontiers in Cardiovascular Medicine*, 8, 614117.
- u, J., Sun, L. L., Wang, J., & Ji, G. (2018). Blood urea nitrogen in the prediction of in-hospital mortality of patients with acute aortic dissection. *Cardiology Journal*, 25(3), 371–376.