Post Date April, 15 2023
One glomerulus and one renal tubule form one nephron, and our kidneys are composed of 2 million such nephrons. (In the picture: The red blood vessel ball is the glomerulus, and the tubular one is the renal tubule!)
Today we will focus on introducing the renal tubules that have the power to concentrate urine!
Let's start with a few questions to test everyone's understanding of renal tubules:
1) What part of the kidney can regenerate?
a. Glomerule b. Renal tubules
2) What are the main functions of renal tubules?
a. Transport b. reabsorption and secretion
3) Without renal tubules, how much urine do we usually produce in a day?
a.1800mlb.180000ml
It doesn't matter. Sasha's Chinese teacher once taught a method: choose a long answer when you don't know what to choose, and generally don't choose a unless you are sure. This accuracy rate will be greatly improved (I wish our lovely teachers a happy Teachers'Day!).
So, the answer is obviously easy to see.
Our renal tubular epithelial cells are the only cells that can regenerate in the kidneys. The renal tubules perform a significant function of urine concentration, filtering 180L (180000ml) of liquid through the kidneys every day. Most of the water and many substances are reabsorbed back by the renal tubules, resulting in only around 1800ml of urine per day. Without the renal tubules, we don't run to death on the way to the restroom, I was killed on the way to grab a drink of water!
That's why some people with minor kidney injuries already have high creatinine levels, and as long as they are detected in a timely manner, they are likely to return to normal again! That's why some people with renal tubular injury are more diligent in running to the bathroom than others, and they always urinate more than once at night.
Kidney puncture can clearly see the problem of renal tubules. So, besides kidney puncture, what other methods do doctors have to determine the problem of renal tubules? This will involve the functional examination of the renal tubules. Those who have undergone the examination will take out the test and learn together.
1. Evaluation of proximal renal tubular function
1) Urine amino acids: When amino acids pass through proximal tubule, most of them will be absorbed back. If the laboratory detects an abnormal increase in this value, it is considered that there is a problem with the proximal renal tubules (but this value is greatly affected by diet, avoid a high protein diet)
2) Urine β 2-Microglobulin: The principle of this is the same as above. But in addition to the possibility of an increase in the number of proximal renal tubules, it is necessary to exclude the possibility of hematological and other tumors causing it β 2. Increased synthesis of microglobulin and increased excretion in urine. (This protein is prone to degradation in urine, and fresh urine must be sent for testing quickly.)
3) Urine α 1- Microglobulin: This is related to urine β 2-Microglobulin has a similar meaning, but it is not easily degraded, compared to β 2-Microglobulin is more stable and an ideal indicator of proximal tubule problems.
4) NAG enzyme: After tubular injury, this value will increase.
5) Urine sugar
2. Evaluation of distal renal tubules
1) Urine specific gravity: This is the most convenient indicator. Routine urine tests indicate that the urine specific gravity must exceed 1.018 once a day, with each time the urine specific gravity is around 1.010 or even below, indicating poor renal tubular concentration function. However, the specific gravity of urine is influenced by the detection method, and some scholars believe that the error of dry chemical method is greater than that of refractive method. In addition, the specific gravity of urine is also affected by pH, temperature, urine sugar, urine protein, and other factors.
2) Urine osmotic pressure: This test is superior to the determination of concentration function by urine specific gravity. 12 hours after water deprivation, the urine osmotic pressure should be at least 600mOsm (kg. H2O), but there should be no interference from diuretics. The use of diuretics will lead to the decrease of urine osmotic pressure
