Deionized water removal rate

The removal rate of non-ionized water (free water) is an ideal renal concentration function test. There are not many hospitals in China that use osmometers. It is very convenient to calculate the urine osmotic pressure by measuring the refractive index of the urine with a refractometer, and then calculate the plasma osmotic pressure by formula, and calculate CH, O. The so-called "free water" means that when the raw urine passes through the thick part of the ascending branch of the renal medulla, sodium chloride is reabsorbed, and water cannot pass through the epithelial cells. At this time, there is "ion-free water" in the renal tubular fluid, that is, The so-called "free water". The osmotic pressure of this liquid is very low. When it flows through the ureter, it is concentrated in large quantities. The amount of free water discharged in a unit time is called the free water removal rate. Because the urine is concentrated in the urinary duct, the free water clearance rate should be negative under normal conditions.