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Laboratory: Clinical Biochemistry
Test Name:
Test Code: OSU
Clinical Information:
Osmolality is a measure of the concentration of solute particles that contribute to the osmotic pressure of a solution. Urine osmolality reflects the concentration of sodium, chloride, potassium and urea. Glucose can also contribute to urine osmolality when present in significant amounts. Comparison of urine osmolality to plasma osmolality can be used in severe electrolyte disturbances to determine the appropriateness and status of water regulation by the kidneys
Collection Devices:
Urine collected without preservative. Similar lab approved leak-proof containers acceptable.
Specimen Required:
Urine: 3.0 mL

Stability 5 days at room temperature, 4 days refrigerated, > 14 days frozen
Reference Values:
50-1200 mmol/kg depending on fluid intake
(mmol/kg = mOsm/kg)
Stat or Routine
See Also:
More Information:
If random urine, specify.
If 24 h urine, measure and record volume.