Deionized water (free water) clearance rate

The ion-free water (free water) clearance rate is an ideal kidney concentration function check, free water = no solute water = no ionized water = pure water. There are not many hospitals using osmometers in China, and it is very convenient to calculate the urine osmotic pressure by measuring the refractive index of urine by using a refractometer. Then, the plasma osmotic pressure is calculated by the formula, and CH, O is calculated. The so-called "free water", that is, when the original urine is thickened by the renal medulla, the sodium chloride is reabsorbed, and the water cannot pass through the epithelial cells. At this time, there is "ion-free water" in the renal tubule fluid, that is, The so-called "free water." The osmotic pressure of this liquid is very low. When flowing through the collecting tube, it is concentrated in a large amount. The amount of free water discharged per unit time is called the free water removal rate. Due to the large concentration of urine in the urinary catheter, the free water clearance rate should be negative when normal. Basic Information Specialist classification: urinary examination classification: urine / kidney function test Applicable gender: whether men and women apply fasting: not fasting Tips: Maintain regular routines and diet to help the inspection go smoothly. Normal value Concentration function test -0.4 ~ -10.7ml / min; dilution function test 1 ~ 9ml / min. Clinical significance Abnormal results: It is generally believed that CH2O can more accurately reflect the degree of renal medulla damage. Since CH2O includes both Mosm and Posm parameters and a urine V variable, V compensates for changes in urine concentration and dilution. (1) Continuous measurement of CH2O can be used as an indication for early diagnosis of renal insufficiency. At this time, CH2O is close to 0. If it returns to a negative value, it indicates a recovery period. This change often occurs earlier than clinical manifestations and general renal function tests. (2) CH2O measurement helps to identify azotemia of non-oliguric renal insufficiency and extrarenal factors, the former CH2O is close to 0, while the latter is normal. (3) acute tubular necrosis (ATN) CH2O is often close to 0, seen in acute blood loss, shock, hypoxia, drug poisoning, extensive burns. (4) Early detection of acute rejection after renal transplantation. People who need to be examined: suspected to be abnormal in renal tubular function. Precautions Taboo before the examination: Maintain regular routines and diet to help the inspection proceed smoothly. Requirements for examination: The patient actively cooperates with the doctor for examination according to the doctor's instructions. The doctor carefully checks and carefully observes the results. Inspection process The doctor uses a refractometer to calculate the urine osmotic pressure by measuring the refractive index of the urine, and then calculates the plasma osmotic pressure by the formula and calculates CH, O. In the case of oliguria, urine and plasma infiltration ratios may cause errors, so that free water clearance (CH2O) can be used. Once the renal enrichment ability is reduced, such as acute renal failure is about to occur, the free water clearance rate can tend to zero value; conversely, the condition improves, CH2O can return to a negative value, and the negative value can reflect the degree of renal function recovery. Therefore, CH2O is often used as an indication for early diagnosis of acute renal insufficiency. Not suitable for the crowd Inappropriate people: Generally, there is no suitable for the crowd. Adverse reactions and risks No related complications or hazards.

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