What is the Difference Between Blood Urea Nitrogen and Blood Urea?

Blood Urea Nitrogen (BUN) and Blood Urea are measurements related to the concentration of urea in the blood. The main difference between the two is that BUN measures the nitrogen component of urea, while Blood Urea measures the whole urea molecule.

In the United States and a few other countries, BUN is measured in mg/dL, and it represents roughly one-half of the blood urea concentration (0.446). In the rest of the world, the whole urea molecule is measured, not just the nitrogen, and it is reported in Standard International units of mmol/L. Urea is approximately twice that of BUN (60/28 = 2.14), so a BUN result of 10 mg/dL is equal to a urea result of 21.4 mg/dL.

Both BUN and Blood Urea are used to assess kidney function and detect potential kidney issues. High BUN or Blood Urea levels can indicate impaired kidney function, which may be caused by various factors such as increased urea production, decreased urea elimination, or kidney damage.

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What is the Difference Between Blood Urea Nitrogen and Blood Urea?

Comparative Table: Blood Urea Nitrogen vs Blood Urea

Blood Urea Nitrogen (BUN) and urea are related but different markers of kidney function. Here is a table summarizing the differences between the two:

Feature	Blood Urea Nitrogen (BUN)	Urea
Definition	BUN is a measure of the amount of urea nitrogen present in the blood.	Urea is a nitrogen-containing waste product that is produced in the liver and excreted by the kidneys.
Formation	Urea nitrogen is a waste product that is produced in the liver and excreted by the kidneys.	Urea is formed in the liver as a byproduct of protein metabolism.
Purpose	BUN test is often used to evaluate kidney function, and high levels can indicate kidney dysfunction, dehydration, or other conditions.	High levels of urea can indicate renal failure or other kidney problems, liver disease, or certain metabolic disorders.
Measurement	BUN is measured in mg/dL in the United States. To convert BUN to a concentration in mmol/L (SI units), multiply by 0.357.	Urea is dissolved in blood and is excreted by the renal tubules. A small amount of urea is also excreted in sweat.

Both BUN and urea are commonly measured in blood tests to assess kidney function and overall health. High levels of BUN or urea can indicate various health issues, such as kidney dysfunction, liver disease, or other conditions.

Guilherme Mazui

Guilherme Mazui is graduated in journalism from the Federal University of Minas Gerais (UFMG) and a master's degree in Communication from the University of São Paulo (USP). In addition, he has experience in advertising writing and has worked as a content editor in several companies.