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HelpTest ID 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.
Useful 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 |
Reference Values
An interpretive report will be provided
Performing 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