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Osmolality, Stool
Test CodeSTOSM
Alias/See Also
Osmolality, Feces
Quest Code
968
Quest Code
968
CPT Codes
84999
Preferred Specimen
1 mL stool collected in plastic leakproof container
Minimum Volume
0.2 mL
Instructions
Formed stool will not be accepted. Freeze within 30 minutes.
Transport Temperature
Frozen
Specimen Stability
Room temperature: unacceptable
Refrigerated: unacceptable
Frozen: not established
Refrigerated: unacceptable
Frozen: not established
Methodology
Freezing Point Depression
Setup Schedule
Monday-Friday Afternoon
Report Available
Next day
Clinical Significance
No age/sex specific ranges for this test. In patients with unexplained diarrhea, osmolalities < 290 mOsm/kg indicate contamination of stool with water or dilute urine or the presence of a gastrocolic fistula and ingestion of hypotonic fluid. Osmolalities > 290 mOsm/kg (up to 600 mOsm/kg) are common because of bacterial metabolism of fecal carbohydrate during storage of the stool sample. Even higher values can be observed with ingestion of large amounts of poorly absorbable carbohydrate or dietary fiber, with fecal contamination by concentrated urine, or with gastrocolic fistula and ingestion of hypertonic fluids.
Performing Laboratory
Quest Diagnostics Nichols Institute
Chantilly, VA
Performing Laboratory
Quest Diagnostics Nichols Institute
Chantilly, VA