What is BUN Known As in Clinical Practice?
BUN stands for Blood Urea Nitrogen, which is a laboratory measurement of the nitrogen component of urea in the blood. 1
Definition and Biochemical Basis
BUN measures the nitrogen portion of urea, which is generated primarily by the urea cycle enzymes in the liver and then eliminated through fluids, especially urine 1
The test specifically quantifies urea nitrogen concentration in blood, typically reported in mg/dL in the United States 2
BUN is mathematically related to blood urea concentration, where urea nitrogen = total urea ÷ 2.14 (since nitrogen comprises approximately 46.7% of urea's molecular weight) 2
Clinical Terminology and Usage
In clinical practice, "BUN" and "blood urea nitrogen" are used interchangeably to refer to this same laboratory value 2, 3
The term is universally recognized in nephrology, critical care, and general medicine as a marker of renal function and metabolic status 1, 4
When measuring dialysis adequacy, clinicians obtain predialysis BUN and postdialysis BUN samples to calculate urea clearance (Kt/V) 2
Important Clinical Context
BUN has been utilized to evaluate renal function for decades, though it reflects more than just kidney function alone 1
The measurement is affected by protein intake, hydration status, liver function, and tissue catabolism, not solely renal clearance 5, 6
In dialysis patients, proper timing and technique for BUN sampling is critical to avoid dilution with saline or heparin, which artificially lowers values 2, 3
Alternative International Terminology
While the question asks about location-specific naming, BUN is the standard term used in clinical practice globally, particularly in North American medical systems 2. Some international laboratories may report total urea concentration instead, but the underlying measurement principle remains the same 1.