What is urea and what role does it play in the body?

Urea is very soluble in water, so it is eliminated from the body through urine. Therefore, the urea index can reflect the state of kidney function.

Urea is the end product of protein metabolism in the body. Urea will be excreted by the body through the urine through the functioning of the kidneys. Odor of urine is caused by the metabolism of urea.
Urea always exists in the body. The daily addition of protein from meat, fish, eggs, ... means the addition of urea.
Exogenous proteins from daily dietary proteins will be converted into amino acids by the digestive system's protease. Then, the amino acids are converted into further products, creating NH3 and CO2. NH3 is a toxin that is converted to urea and some toxins in the liver. If the liver is dysfunctional or impaired, it will affect the process of converting NH3 into urea, gradually causing NH3 to accumulate, creating a large amount of toxins, affecting the nervous system, increasing the risk of encephalopathy. due to ammonia leads to hepatic coma.
In addition to being eliminated from the body through urine, urea can also be excreted through sweat (a very small amount). On average, an adult will excrete about 30g of urea/day through the urine.

Normal blood urea nitrogen is at 0.2 - 0.4 g/l, can increase to about 0.1 - 0.5 g/l and is still assessed as normal kidney function. If the urea index exceeds the upper limit, it means that kidney function is affected.
Urea in blood can also change after eating. If you eat a lot of protein-rich foods, the blood urea index will increase. Therefore, when testing blood urea index, people usually do it in the morning, when they have not eaten anything so as not to affect the results.

Urea is less toxic, so even a high blood urea index is not very dangerous to human health. The blood urea nitrogen index is commonly used to assess kidney function. If blood urea is high, kidney function is poor. If the blood urea nitrogen is normal as mentioned above, then the kidney function is good.
In addition to the causes of impaired kidney function, there are many causes that affect the blood urea nitrogen index such as: Stress, heart attack, burns, gastrointestinal bleeding, urine flow obstruction, body dehydration ...
People with severe liver disease, malnutrition, pregnant women may have low blood urea levels. However, the urea index test is not used to diagnose these conditions.