Normal renal function

The kidneys are very important organs that promote metabolism and maintain normal endocrine function. However, many people now have kidney problems, especially kidney deficiency is very common. Kidney function can maintain the normal metabolic function of our body. Kidney function tests also include many items, such as blood urea nitrogen, blood creatinine, urine albumin, etc. Let's take a look at the normal values ​​of kidney function.

There are many items in the renal function test. I believe that everyone is not very clear about some of the data after the renal function test, and does not know what the normal value of renal function is. Let us look at the normal value of each item in the renal function test to let us understand what problems are with our kidneys.

Normal renal function

1. Endogenous creatinine clearance test, which is more common in renal function tests to check the degree of glomerular damage:

Before and on the day of the test, the subjects were fed a low-protein diet for three days, and no meat was eaten and strenuous exercise was avoided. The subjects urinated completely at 8 a.m. on the test day, and then collected the urine in a clean container containing toluene as a preservative for 24 hours until 8 a.m. the next morning. On the test day, 2-3 ml of venous blood was drawn. Send blood and urine for examination at the same time. The normal range is 109~148 L/24 hours (or 80~120 ml/minute), and the average value is 128 L/24 hours (or 100 ml/minute). A clearance rate less than 80% of the normal value indicates impaired glomerular filtration function. A clearance rate of 70-51 ml/min is considered slightly reduced, 50-31 ml/min is considered moderately reduced, and less than 30 ml/min is considered severely reduced. A clearance rate of 20-11 ml/min indicates early-stage renal insufficiency, 10-6 ml/min indicates late-stage renal insufficiency, and less than 5 ml/min indicates end-stage renal insufficiency.

2. Blood urea nitrogen and blood creatinine are commonly used tests for renal function:

Take 1 ml of venous blood, inject it into the anticoagulant tube, and mix it thoroughly. Normal blood urea nitrogen is 9~20 mg/L and blood creatinine is 1~2 mg/L. Various serious kidney diseases cause renal insufficiency and the level of all proteins increases. Upper gastrointestinal bleeding, severe infection and excessive protein in the diet can all cause a temporary increase in blood urea nitrogen. Blood creatinine concentration is less affected by factors such as diet. When it is significantly elevated, it indicates a poor prognosis.

3. Phenol red (PSP) excretion test:

Do not use aspirin, penicillin or other drugs before the test. Diuretic beverages such as tea and coffee should be avoided before and during the test. Instruct the patient to urinate 20 minutes before the test, then drink 300-400 ml of water, and no longer drink water. Use a 1 ml syringe to accurately draw 1 ml of 0.6% phenol red solution and inject it intravenously. Collect urine once at 15, 30, 60, and 120 minutes after injection, collect them into clean specimen bottles, and send them for testing in time. Normally, the excretion rate is 25% or higher 15 minutes after injection, and the total excretion rate is greater than 55% in 120 minutes. If it is lower than the normal value, it indicates renal damage. Diseases that can cause changes in renal blood flow, such as heart failure, severe hypertension and pyelonephritis, will also reduce the excretion rate of phenol red.

4. Urine concentration and dilution function test:

The patients ate normal diet on the experimental day. Urine is voided every three hours for 24 hours day and night and collected in clean specimen bottles. The normal ratio of daytime urine volume to nighttime urine volume is 3~4:1; the nighttime urine volume in 12 hours does not exceed 750 ml; the maximum specific gravity of urine is above 1.020. The difference in maximum specific gravity shall not be less than 0.009. Nocturnal urine volume exceeds 750 ml, which is often an early manifestation of renal insufficiency; the highest specific gravity less than 1.08 indicates renal concentrating dysfunction; the specific gravity of each specimen is very different, and the urine specific gravity is mostly fixed at around 1.010, indicating a serious disorder of renal concentrating function; the daytime urine specific gravity is fixed at 1.018 or higher, which is mostly a dehydrated patient.

The function of the kidneys is very powerful, but many of the current lifestyles are unscientific and can cause great harm to our kidneys. Kidney disease is also very common. When there is a problem with the kidneys, kidney function is generally checked. The above introduction to the normal values ​​of kidney function can help us better understand what problems are with our kidneys.