Find Locations
For hours, walk-ins and appointments.Special Instructions
State patient's age on the request form.
Expected Turnaround Time
1 - 3 days
Turnaround time is defined as the usual number of days from the date of pickup of a specimen for testing to when the result is released to the ordering provider. In some cases, additional time should be allowed for additional confirmatory or additional reflex tests. Testing schedules may vary.
Related Documents
Specimen Requirements
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
Collection
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.
Storage Instructions
Refrigerate
Stability Requirements
Temperature | Period |
|---|---|
Room temperature | 14 days |
Refrigerated | 14 days |
Frozen | 14 days |
Freeze/thaw cycles | Stable x3 |
Causes for Rejection
Hemolysis; EDTA plasma submitted
Test Details
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.
Methodology
Freezing point depression
Reference Interval
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
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.
Footnotes
1. Weisberg HF. Unraveling the laboratory model of a syndrome: The osmolality model. In: Young DS, Hicks J, Nipper H, et al, eds. Clinician and Chemist. The Relationship of the Laboratory to the Physician. Washington, DC: American Association of Clinical Chemistry;1979:200-243.
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 |
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The LOINC® codes are copyright © 1994-2021, Regenstrief Institute, Inc. and the Logical Observation Identifiers Names and Codes (LOINC) Committee. Permission is granted in perpetuity, without payment of license fees or royalties, to use, copy, or distribute the LOINC® codes for any commercial or non-commercial purpose, subject to the terms under the license agreement found at https://loinc.org/license/. Additional information regarding LOINC® codes can be found at LOINC.org, including the LOINC Manual, which can be downloaded at LOINC.org/downloads/files/LOINCManual.pdf