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Urine osmolality is a test to determine the mass of solutes per unit volume of urine by measuring the concentration of solutes in the urine. This is a highly accurate method and plays an effective role in supporting the diagnosis of pathology instead of the urine density test.
1. What is urinary osmotic pressure?
Urinary osmolality represents the concentration of solutes in the urine, which is a value that shows the concentration of ions such as chloride, sodium, urea or potassium. Urinary glucose also affects urinary osmolality when urine glucose is elevated. Urine osmolality in a normal person also partly reflects urinary osmolality
Evaluation of urinary osmolality allows the doctor to know the patient's kidney's ability to maintain the body's water-electrolyte balance . Comparing urinary osmolality with blood osmolality also helps to assess the kidney's ability to regulate or detect abnormal solutes in the urine. The normal urinary osmolality/plasma osmolality ratio would be about 1/3.
Measurement of urinary osmolality will be indicated in the following cases:
Diagnosis and evaluation of fluid and electrolyte abnormalities in the body Determine fluid needs in the body
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2. How to measure urine osmolality?
About patient samples: the specimen used to measure urinary osmolality is 24-hour urine, patients do not need to fast before measuring urinary osmolality for random urine samples but need to declare Identify medications taken by the patient within the previous 72 hours (especially diuretics)
How to measure urine osmolality:
Urine osmolality will be measured with an osmometry Measurement rule: based on the change in the freezing point of urine relative to water Calculating urinary osmolality: every 1 mOsm/kg will reduce the freezing point to 0.001858 °C, so the freezing point of urine The lower the osmolality, the higher the urinary osmolality. If a urine osmolality meter is not available, it can be estimated by the following formula: Urinary osmolality = [Na + K + Urea] is the total concentration of 3 substances in the urine in mmol/l
3. Significance of abnormalities in urinary osmotic pressure:
For random urine specimens, urine osmolality will be around 50-1200 mOsm/kg H2O or 50-1200 mmol/kg
For specimens after fasting 12-14 hours, normal urine osmolality usually: above 850 mmol/kg
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Cases of increased urinary osmolality include:
Dehydration Abnormal ADH secretion syndrome Diabetes mellitus Hypernatremia Addison's disease Congestive heart failure Diarrhea, edema Cirrhosis Liver acidosis, Diet high in protein Cases of decreased urinary osmolality include:
Drinking a lot of water Diabetic insipidus Acute renal failure Glomerulonephritis Hyperaldosteronism Hypercalcemia Hypokalemia Multiple myeloma Sickle cell anemia Urinary tract obstruction
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4. Clinical significance of urinary osmolality measurement:
Urinary osmolality measures the number of osmotically active particles in 1 kg of urine reflecting the kidney's ability to concentrate urine. Therefore, the test is especially useful to evaluate the state of increased or decreased sodium in the body, and also helps to differentiate between prerenal azotemia and ischemic acute tubular necrosis. However, in some cases, the results may change due to factors such as:
Use of antibiotics Use of antidepressants, psychiatric treatment Use of cancer chemotherapy, dextran, diuretics, glucose, mannitol and contrast agents Periodic health check-ups help in early detection of diseases, thereby creating a treatment plan for optimal results. Currently, Vinmec International General Hospital has general health checkup packages suitable for each age, gender and individual needs of customers with a reasonable price policy, including:
Health checkup package diamond general health check-up package Vip special health check-up package Comprehensive general health check-up package Standard general health check-up package Patient's examination results will be returned to your home. After receiving the results of the general health examination, if you detect diseases that require intensive examination and treatment, you can use services from other specialties at the Hospital with quality treatment and services. outstanding customer service.
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