ELECTROLYTE & OSMOLALITY PROFILE, FECES
- Code
- 000.0000
- Name
- ELECTROLYTE & OSMOLALITY PROFILE, FECES
- Category
- None
- Department
- Send-Out
- Start Date
- Expiration Date
- Synonyms
- CPT Codes
- 84999 x 2, 84302, 83735
- Site
- SBMF
- Reference Test
- 44526
Specimen Information
- Type
Routine random or 24-hour feces collection
Sample must be liquid, test is not indicated for patients passing non-liquid feces
Transfer sample aliquot to plastic screw-top container. Freeze and transport frozen.
- Volume
10.0 g
- Transport Info
Transfer sample aliquot to plastic screw-top container. Freeze and transport frozen.
- Fasting Required?
- False
- Patient Instructions
- Reference Range
See report
- Methodology
Ion-Selective Electrode, Freezing Point Depression
Clinical Significance
Normal fecal fluid has an osmolality close to that of plasma (i.e., 290 mOsm/kg), a sodium concentration of about 30 mmol/L, a potassium concentration of about 75 mmol/L, and a magnesium concentration between 12 to 240 mg/dL (depending on diet) although it is usually less than 110 mg/dL. A fecal sodium greater than 90 mmol/L and an osmolal gap less than 50 mOsm/kg suggests secretory diarrhea or osmotic diarrhea due to sodium-containing laxatives. A fecal sodium less than 60 mmol/L and an osmolal gap greater than 100 mOsm/kg suggests osmotic diarrhea. Fecal sodium greater than 150 mmol/L and osmolality greater than 400 mOsm/kg suggests contamination with concentrated urine. Fecal osmolality less than 250 mOsm/kg suggests contamination with hypoosmotic urine or water.