What is the normal value of urea nitrogen and creatinine?

To determine whether kidney function is normal, we need to understand the normal range of urea nitrogen and creatinine. When urea nitrogen exceeds normal values, everyone needs to be aware that there is a high probability that there is a problem with the kidneys. When the body experiences symptoms such as edema, fatigue, etc., especially when the skin on the ankle is dimpled when pressed, go to the hospital as soon as possible to check the normal values ​​of urea nitrogen and creatinine.

Under normal circumstances, the ratio of blood urea nitrogen to creatinine (urea nitrogen/Scr) is about 10. A high-protein diet, high catabolic state, dehydration, renal ischemia, insufficient blood volume and certain acute glomerulonephritis can increase the ratio, even to 20-30. A low-protein diet and liver disease often lower the ratio, which is called hypoazotemia.

What is the normal value of urea nitrogen?

Generally speaking, the fasting urea nitrogen of a normal adult is 3.2-7.1mmol/L (9-20mg/d1). Reference value of urease indophenol method: M (male): 2.89-7.85mmol/L L (female): 2.78-7.32mml/L; reference value of urease-sodium reagent colorimetric method: 3.21-6.07mmoI/L

The normal value of urea nitrogen varies slightly in different places. It is generally believed that the normal value of urea nitrogen is 2.86-7.14mmol/L. 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 increased blood urea nitrogen. If the extra-renal factors can be ruled out, urea nitrogen of 21.4mmol/L (60mg/d1) is one of the diagnostic indicators of uremia. The level of urea nitrogen is easily affected by diet and renal blood flow. If there are protein decomposition factors - infection, intestinal bleeding, hyperthyroidism, etc., the urea nitrogen can be increased. When the glomerular filtration rate drops to 1/2-1/3 of the normal level, urea nitrogen gradually increases. Under normal circumstances, the ratio of blood urea nitrogen to blood creatinine is 10:1. The reasons for the high ratio include gastrointestinal bleeding, hemolysis, heart failure and enhanced tissue decomposition (burns, high fever, cortical hormone treatment, etc.), which are mostly caused by prerenal factors. A decreased ratio is seen in insufficient protein intake, severe liver and kidney dysfunction, etc.

Urea nitrogen concentration is affected by many factors, which can be divided into two aspects: physiological factors and pathological factors.

1. Physiological factors: A high-protein diet can cause an increase in serum urea nitrogen concentration, which is 2-3 mg/dL higher in men than in women on average.

2. Pathological factors:

a． Prerenal: severe vomiting, pyloric obstruction, massive gastrointestinal bleeding, intestinal obstruction and long-term diarrhea, etc.

b. Renal: acute glomerulonephritis, chronic nephritis, chronic pyelonephritis, late stage renal disease, renal failure and toxic nephritis.

c. Post-renal diseases: prostate enlargement, urinary tract stones, urethral stenosis, urinary tract compression caused by bladder tumors, etc.