Water forbidden test

The water-free test means that after the water is actively limited within a certain period of time (usually 1 to 2 weeks), the water is completely banned from the night before the test. If the water can not be tolerated, the water can be stopped from 4 am. After the normal person's water ban, the blood osmotic pressure increases and the circulating blood volume decreases. Both of them stimulate the release of AVP, so that the urine volume decreases, the urine specific gravity increases, the urine penetration increases, and the blood osmotic pressure does not change much. The clinical observation of the water-free test began at 8 am, observing body weight, heart rate, blood pressure, urine volume, urine specific gravity, urine and blood osmotic pressure. The urine volume of patients with complete pituitary diabetes insipidus was not reduced after the water was banned. Does not rise, urine osmotic pressure is not high, and even lower than the blood osmotic pressure level, there is a weight loss, such as a decline greater than 3% of body weight should immediately stop the test. In patients with partial pituitary diabetes insipidus, the urine volume may be partially reduced during the test, and the urine specific gravity or urine osmotic pressure may increase to some extent, but it may not reach the normal level. Renal diabetes insipidus has little change in urine volume, urine specific gravity, and urine osmotic pressure during the test. Basic Information Specialist classification: urinary examination classification: urine / kidney function test Applicable gender: whether men and women apply fasting: not fasting Reminder: Maintain regular routines and diet before the examination to help the inspection proceed smoothly. Normal value Normally, after drinking water, the changes of body weight, blood pressure and blood osmotic pressure are less than 295mOsm/kg.H2O, and the osmotic pressure can be greater than 800mOsm/kg. After H2O injection of vasopressin, the urine osmotic pressure does not increase by more than 9%. Clinical significance Abnormal results: mental polydipsia is close to or similar to normal people. Patients with central diabetes insipidus have a rest loss of >3% after water inhibition. In severe cases, blood pressure can be reduced, irritability and other symptoms can be divided into partial diabetes collapse according to the severity of the disease. The osmotic flattening value of the former and complete diabetes insipidus is not higher than 300mOsm/kg.H2O, the urine osmotic pressure may slightly exceed the plasma osmotic pressure, and the urine osmotic pressure may continue to rise after the injection of vasopressin. The plasma osmotic flattening value is greater than 300mOsm/kg.H2O, the urine osmotic pressure is lower than the blood osmotic pressure, and the urine osmotic pressure is increased by more than 9% or even multiplied after the injection of vasopressin. In the case of kidney nourishing diabetes, the urine can not be concentrated and concentrated after the water is banned, and there is still no reaction after the injection of vasopressin. People who need to be examined: suspected to be dysfunctional glomeruli. Precautions Taboo before the examination: Maintain regular routines and diet to help the inspection proceed smoothly. Requirements for the examination: The doctor asks the patient to dispel the ideological concerns and cooperate with the trial. According to the doctor's instructions, the patient actively cooperated with the doctor for examination, and the doctor carefully examined and carefully observed the results. Inspection process The water is banned for 6 to 16 hours (usually 8 hours of water ban) depending on the severity of the illness. Body weight, blood pressure plasma osmotic pressure and urine specific gravity were measured before the test. After that, the urine output per urine, urine specific gravity and urine osmotic pressure will not change much in two consecutive urine changes. When the urine osmotic pressure changes <30mOsm/kg.H2O, the endogenous AVP secretion has reached the maximum value (mean). At this time, the plasma osmotic pressure was measured, and immediately after the subcutaneous injection of the aqueous vasopressin 5u, the urine was taken and the urine volume and urine osmotic pressure were measured. 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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