Osmolality
Formal name: Osmolality (plasma, urine, and stool)
Related tests: BUN; Creatinine; Electrolytes; Glucose; Sodium; Emergency and Overdose Drug Testing; Osmotic gap; Osmolal gap
At a Glance
Why Get Tested?
To help evaluate the body’s water and electrolyte balance and to help investigate hyponatremia and increased or decreased urine production; to detect the ingestion of certain toxins (such as methanol); to monitor the effectiveness of treatment for conditions affecting osmolality; to help determine the cause of chronic diarrhea
When to Get Tested?
When a patient has a low sodium level; when a patient is taking mannitol; when a doctor suspects that a patient may have ingested a toxin such as methanol or ethylene glycol; when a patient is producing significantly increased or decreased amounts of urine; when a patient has chronic diarrhea
Sample Required?
A blood sample drawn from a vein in your arm and/or a random urine sample; sometimes a fresh, liquid stool sample
Test Preparation Needed?
None
