What is the normal value of urea nitrogen?

Urea is a relatively common chemical substance with a wide range of uses, and is commonly used in agriculture and medical fields. The urea content in the human body is also relatively high. Among them, urea nitrogen is an indispensable substance and plays a great fundamental role in physical health. Let's take a look at the normal value of urea nitrogen. I hope everyone can understand this explanation.

Urea nitrogen and blood creatinine are the two most important indicators of renal function. The high and low values ​​of urea nitrogen reflect the good or bad of kidney function. A urea nitrogen value higher than the normal value means that the urea nitrogen is high.

Urea nitrogen is the main end product of protein metabolism in the human body. Amino acids are deaminated to produce NH3 and C02, both of which are synthesized into urea in the liver, with 0.3g of urea produced per gram of protein metabolism. The nitrogen content in urea is 28/60, almost half. Usually the kidneys are the main organ for excreting urea. After being filtered through the glomerulus, urea can be reabsorbed in each segment of the tubule. However, the faster the urine flow rate in the renal tubule, the less reabsorption occurs, which means that the maximum clearance rate has been reached.

Normal value:

The normal fasting urea nitrogen of an adult is 3.2-7.1mmol/L (9-20mg/dl). Various renal parenchymal lesions, such as glomerulonephritis, interstitial nephritis, acute and chronic renal failure, intrarenal space-occupying and destructive lesions can all increase blood urea nitrogen. Multiple extra-renal factors can also cause elevated blood urea nitrogen. If extra-renal factors can be ruled out, a urea nitrogen level of 21.4 mmol/L (60 mg/dl) is one of the diagnostic indicators for uremia.

When renal function is impaired, blood urea nitrogen increases, but it is not the only clinical manifestation. Blood creatinine will also increase. There will also be clinical manifestations such as increased blood pressure, loss of appetite, bleeding gums, electrolyte imbalance, metabolic acidosis, and abnormal urine tests. Therefore, increased urea nitrogen alone cannot be considered renal insufficiency.

For patients with kidney disease, there are two situations in which blood urea nitrogen is high. The most common is renal insufficiency, including acute renal insufficiency and chronic renal insufficiency, which is mainly caused by renal damage and the inability of urea nitrogen to be excreted from the urine. Secondly, a small number of patients with acute nephritis and nephrotic syndrome may also have transient increases in blood urea nitrogen, which is mainly seen in severe edema. Due to oliguria, the urea nitrogen in the blood cannot be excreted with urine and accumulates in the blood.