Urine osmolality measures the number of osmotically active particles in the urine or urine concentration, reflecting the kidneys' ability to concentrate urine. The test helps assess fluid and electrolyte balance and determine the body's fluid requirements. It is also instrumental in evaluating hyponatremia and hypernatremia and distinguishing prerenal azotemia from acute ischemic tubular necrosis. After an overnight fast, urine osmolality should be at least three times the osmolality of the blood.
Medications that affect the measurement: antibiotics, antidepressants, antipsychotics, bromocriptine, chemotherapeutics, dextran, diuretics, glucose, mannitol, and contrast agents.
Possible Interpretation of Pathological Values
- Increase: Addison's disease, azotemia, congestive heart failure, dehydration, diabetes mellitus, diarrhea, edema, glycosuria, liver cirrhosis, high-protein diet, hyperglycemia, hypernatremia, ketoacidosis, postoperative, prerenal azotemia, sodium overload, syndrome of inappropriate antidiuretic hormone secretion (SIADH), uremia
- Decrease: Acute renal failure, aldosteronism, diabetes insipidus, edema, fever, glomerulonephritis, hypercalcemia, hypokalemia, hyponatremia, multiple myeloma, fluid overload, sickle cell anemia, urinary tract obstruction, water intoxication
Important Note
Laboratory test results are the most critical parameter for diagnosing and monitoring all pathological conditions. Between 70 to 80% of diagnostic decisions are based on laboratory tests. Correctly interpreting laboratory results allows a doctor to distinguish "healthy" from "diseased."
Laboratory test results should not be interpreted from the numerical result of a single analysis. Test results should be analyzed based on each case and family history, clinical findings, and the results of other laboratory tests and information. Your physician should explain the importance of your test results.
At Diagnostiki Athinon, we answer any questions you may have about the test you perform in our laboratory and contact your doctor to ensure you receive the best possible medical care.
