Urea nitrogen is the end product of protein metabolism in the body. Protein is produced in the liver as urea, which is excreted in the urine through glomerular filtration. In clinical practice, glomerular function and liver function are evaluated by measuring the plasma level of urea nitrogen. Low urea nitrogen can be seen in reduced urea production or excessive urea excretion: I. Reduced urea production: 1. Liver function damage: Low urea nitrogen can be seen in patients with liver disease such as hepatitis and cirrhosis, where the liver cells are destroyed, resulting in the inability of protein to produce urea in the liver, resulting in reduced urea nitrogen in the blood. At this time, patients often have jaundice, weakness, anorexia and other manifestations, such people appear low urea nitrogen, it is recommended to combine liver function, hepatitis B five, liver ultrasound and other tests to confirm the diagnosis and treatment, can be under the guidance of the doctor to take anti-viral drugs, liver protection drugs control; 2, too little protein intake: long-term intake of protein is low, the body does not have enough protein decomposition, which leads to reduced urea production, it is recommended that more intake High quality protein, such as eggs, beans and dairy products, etc.; 3, increased protein consumption: a large amount of maternal protein needs to be provided to the fetus in the second trimester, the body is in a negative nitrogen balance, resulting in a decrease in urea production, it is recommended that the appropriate amount of high protein, high nutrition diet. During infancy and early childhood, protein is relatively insufficient, and urea is also produced less, so it is recommended to consume protein diet appropriately. Second, excessive urea excretion: 1, physiological excretion of excess: may be due to the detection of urea nitrogen before the test, the subject drink a lot of water, resulting in blood is diluted, causing an increase in urine, the relative increase in urea excretion, the situation of low urea nitrogen, without special treatment, can be checked again urea nitrogen; 2, pathological polyuria: such as early diabetes, uremia and other diseases, as well as kidney diseases such as glomerulonephritis polyuria period. It can also lead to an increase in urine, thus excreting a large amount of urea and making the urea nitrogen in the blood low. While diabetes is generally associated with genetics and dietary habits, uremia may be associated with genetics and hypothalamic neuropathy, among other factors. Patients may show signs of thirst, excessive drinking and polyuria, and may take anti-diuretic drugs under the guidance of a doctor, or perform hormone replacement therapy, etc. In addition, it may be caused by psychological factors such as primary irritable thirst that leads to increased urination, which leads to excessive urea excretion, thus causing low urea nitrogen in the plasma. In this case, we need to actively cooperate with the doctor to treat the primary disease, such as controlling emotions, reducing water consumption, and taking glucose-lowering drugs or insulin injections as prescribed by the doctor to control blood sugar levels.