Osmolality, Fecal
| Osmolality, Fecal | | | |
| Number | | 120071 |
| CPT | | 84999 |
| Synonyms | | Fecal Osmolality |
| Specimen | | Liquid stool, frozen |
| Volume | | 15 mL |
| Container | | Small plastic container; do not use large paint can. |
| Collection | | Stool sample must be collected without addition of water. |
| Storage Instructions | | Freeze |
| Causes for Rejection | | Stool not liquid; stool contaminated with urine; paint can submitted |
| Reference Interval | | Not established |
| Use | | Distinction of osmotic from nonosmotic secretory diarrhea. A large deficit (>50 mOsm/kg) in the calculated osmolality (twice the sum of the stool sodium and stool potassium) from the measured stool osmolality indicates osmotic diarrhea. |
| Methodology | | Freezing point depression |
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