What is the difference between urea and urea nitrogen?

Urea and urea nitrogen are easily confused just from their names. Although these two substances are both related to urea, they have completely different properties and characteristics in many aspects. This is a point that many people cannot figure out. Let’s take a look at the differences between urea and urea nitrogen. I hope everyone can understand this aspect. I hope everyone can understand this aspect.

Urea:

It is the final product of the metabolism of protein and its constituent amino acids. During protein catabolism, proteins are broken down into amino acids, which are then deaminated and combined with ammonia in the liver to form urea, which is the most important way to eliminate excess nitrogen in the body. At the same time, urea is the most abundant non-protein nitrogenous substance in the body.

Urea determination is the most widely used test for evaluating renal function. It is often used in conjunction with creatinine to differentiate between prerenal hyperurea (cardiac decompensation, dehydration, increased protein breakdown), renal hyperurea (glomerulonephritis, chronic nephritis, polycystic kidney disease, nephrosclerosis, tubular necrosis) and postrenal hyperurea (urinary tract obstruction).

Urea nitrogen:

It and the level of blood creatinine together reflect the state of kidney function. Generally speaking, the higher their levels are, the more serious the kidney function damage is. However, blood urea nitrogen levels are easily affected by diet and urine volume and may fluctuate greatly, while blood creatinine is less affected by these factors.

Urea nitrogen test is generally performed when glomerulonephritis, pyelonephritis, renal ischemia, urinary tract obstruction, uremia, dehydration, heart disease, gastrointestinal bleeding, leukemia, hyperthyroidism, aspergillosis, gout, alcoholism, liver cancer, malnutrition, toxic hepatitis, etc. are suspected, diagnosed or excluded.

It is easy for testers to understand the difference between urea and urea nitrogen without more explanation, but it is not easy for clinicians. Many authoritative textbooks still teach students to call urea urea nitrogen, which requires us to do long and hard work.

Conversion: mg/dL urea nitrogen × 0.0.357 = mmol/L urea nitrogen