The blood urea nitrogen (BUN) to creatinine ratio is a clinical laboratory value that estimates kidney function by comparing the levels of two substances in the blood: blood urea nitrogen and creatinine. It is determined by dividing the BUN value (measured in mg/dL) by the creatinine value (measured in mg/dL). For instance, if a patient’s BUN is 20 mg/dL and their creatinine is 1 mg/dL, the calculated value would be 20:1.
This ratio can provide valuable insights into the potential causes of kidney dysfunction. An elevated ratio may indicate dehydration, gastrointestinal bleeding, or increased protein catabolism, while a decreased ratio can be observed in liver disease or malnutrition. Historically, this measure has been used as a readily available and inexpensive method for assessing renal health and guiding further diagnostic investigations.
