Test Details
Methodology
Freezing point depression
Result Turnaround Time
1 - 3 days
Use
Evaluate electrolyte and water balance, hyperosmolar status, and hydration status; evaluate dehydration, acid-base balance; evaluate seizures; clue to alcoholism, methanol toxicity, ethylene glycol ingestion; evaluate antidiuretic hormone function, liver disease, hyperosmolar coma, evaluate hypernatremia. Osmolarity measures the concentration of particles in solution.
Special Instructions
State patient's age on the request form.
Specimen Requirements
Custom Additional Information
High serum osmolality can result from hypernatremia, dehydration, hyperglycemia, mannitol therapy, azotemia, ingestion of ethanol, methanol, ethylene glycol. Thus, osmolality has a role in toxicology and in coma evaluation. Elevated serum osmolality with normal sodium suggests possible hyperglycemia, uremia, or alcoholism.1
Low serum osmolality may be secondary to overhydration, hyponatremia, syndrome of inappropriate antidiuretic hormone secretion (SIADH) with carcinoma of lung and other entities.
Specimen
Serum or plasma
Volume
2 mL
Minimum Volume
0.2 mL (Note: This volume does not allow for repeat testing.)
Container
Red-top tube, gel-barrier tube, or green-top (heparin) tube
Storage Instructions
Refrigerate
Causes for Rejection
Hemolysis; EDTA plasma submitted
Collection Instructions
Pediatric: Blood drawn from heelstick for capillary. Separate serum or plasma from cells as soon as possible after clot formation. Transfer specimen to a plastic transport tube.
Stability Requirements
Temperature | Period |
|---|---|
Room temperature | 14 days |
Refrigerated | 14 days |
Frozen | 14 days |
Freeze/thaw cycles | Stable x3 |
Reference Range
Neonatal: may be as low as 266 mOsm/kg; 0 to 60 years: 275−295 mOsm/kg; 61 years and older: 280−301 mOsm/kg
Footnotes
LOINC® Map
| Order Code | Order Code Name | Order Loinc | Result Code | Result Code Name | UofM | Result LOINC |
|---|---|---|---|---|---|---|
| 002071 | Osmolality | 2692-2 | 002071 | Osmolality | mOsmol/kg | 2692-2 |
| Order Code | 002071 | |||||
| Order Code Name | Osmolality | |||||
| Order Loinc | 2692-2 | |||||
| Result Code | 002071 | |||||
| Result Code Name | Osmolality | |||||
| UofM | mOsmol/kg | |||||
| Result LOINC | 2692-2 |