Urea nitrogen 8.14mmol/L is not normal, its higher than normal value is on the high side, the normal range of adults is 3.2~7.1mmol/L. The purpose of urea nitrogen test is to diagnose organic renal impairment, such as various primary glomerulonephritis and other causes of chronic renal failure, acute renal failure and so on. High urea nitrogen may be physiologic or pathologic. Physiological high urea nitrogen is usually due to high protein diet, because urea nitrogen is the middle and end product of protein metabolism in the body. Drugs such as glucocorticoids and tetracyclines have a certain degree of nephrotoxicity, and urea nitrogen is also elevated with this drug. Pathological elevation of urea nitrogen, such as renal failure when the renal parenchyma is damaged, the glomerular filtration rate decreases, the blood urea nitrogen concentration will increase; congestive heart failure, renal artery stenosis, etc. will make the renal perfusion decrease, blood urea nitrogen increases. Abnormal thyroid function, gastrointestinal bleeding and other diseases will lead to a decrease in effective circulating blood volume, glomerular filtration rate decreased, urea nitrogen increased. It is recommended that patients with abnormal urea nitrogen should go to the hospital in time to improve the relevant examinations under the guidance of the doctor, and should be actively treated if it is caused by pathological factors.