Home
HelpTest Code OSG_F Osmotic Gap, Feces
Ordering Guidance
This test is only clinically valid if performed on watery specimens. In the event a formed fecal specimen is submitted, the test will not be performed.
Specimen Required
Patient Preparation: No barium, laxatives, or enemas may be used for 96 hours prior to start of, or during, collection.
Supplies: Stool containers - 24, 48, 72 Hour Kit (T291)
Collection Container/Tube: Stool container
Specimen Volume: 10 g
Collection Instructions: Collect a very liquid fecal specimen.
Secondary ID
610305Useful For
Workup of cases of chronic diarrhea
Differentiating osmotic from non-osmotic causes of chronic diarrhea.
Profile Information
| Test ID | Reporting Name | Available Separately | Always Performed |
|---|---|---|---|
| NA_F | Sodium, F | No | Yes |
| K_F | Potassium, F | No | Yes |
| OG_F | Osmotic Gap, F | No | Yes |
Method Name
OG_F: Calculation
NA_F, K_F: Indirect Ion-Selective Electrode (ISE) Potentiometry
Reporting Name
Osmotic Gap, FSpecimen Type
FecalSpecimen Minimum Volume
5 g
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Fecal | Frozen (preferred) | 14 days | |
| Refrigerated | 7 days | ||
| Ambient | 48 hours |
Reject Due To
All specimens will be evaluated at Mayo Clinic Laboratories for test suitability.Reference Values
An interpretive report will be provided
Specimen Retention Time
7 daysPerforming Laboratory
Mayo Clinic Laboratories in Rochester
Test Classification
This test has been modified from the manufacturer's instructions. Its performance characteristics were determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the US Food and Drug Administration.CPT Code Information
84302-Sodium
84999-Potassium
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| OSG_F | Osmotic Gap, F | 88697-8 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| NA_F | Sodium, F | 15207-4 |
| K_F | Potassium, F | 15202-5 |
| OG_F | Osmotic Gap, F | 73571-2 |
Day(s) Performed
Monday, Thursday