7AlphaC4
Test Mnemonic
7ALPC4
CPT Codes
- 82542 - QTY (1)
Aliases
- 7AC4
- bile acid diarrhea
Includes
- 7AlphaC4
Performing Laboratory
LabCorp
Specimen Requirements
| Volume | Type | Container | Collect Temperature | Transport Temperature | Special Instructions |
|---|---|---|---|---|---|
| 0.5 mL | Serum | SST (Gold) | Frozen | Collect prior to 9am after overnight fast. Separate serum from cells within 2 hours of collection and transfer to standard aliquot tube. |
Alternate Specimen Requirements
| Volume | Type | Container | Collect Temperature | Transport Temperature | Special Instructions |
|---|---|---|---|---|---|
| 0.5 mL | Serum | No additive (Red) | Frozen | Collect prior to 9am after overnight fast. Separate serum from cells within 2 hours of collection and transfer to standard aliquot tube. | |
| 0.5 mL | Plasma | EDTA (Lavender) | Frozen | Collect prior to 9am after overnight fast. Separate plasma from cells within 2 hours of collection and transfer to standard aliquot tube. | |
| 0.5 mL | Plasma | Sodium or Lithium heparin (Green) | Frozen | Collect prior to 9am after overnight fast. Separate plasma from cells within 2 hours of collection and transfer to standard aliquot tube. |
Minimum Specimen Requirements
| Volume | Type | Container | Collect Temperature | Transport Temperature | Special Instructions |
|---|---|---|---|---|---|
| 0.4 mL |
Stability
| Environmental Condition | Description |
|---|---|
| Frozen | After separation from cells: 9 days |
| Refrigerated | After separation from cells: 9 days |
| Ambient | After separation from cells: 24 hours |
Days Performed
Varies
Turnaround Time
11 - 12 days
Methodology
| Name | Description |
|---|---|
| Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS) |
Special Info
Collection prior to 9am after overnight fast.
Clinical Info
This test is useful as a surrogate measure of stool bile acids (BA) and elevated levels may be diagnostic for bile acid malabsorption (BAM), also known as bile acid diarrhea (BAD). Overall, the data indicates that fasting serum C4 has excellent negative predictive value when normal in ruling out bile acid diarrhea. Key limitations of the assay include the need to use first morning fasting samples (before 9AM) because of diurnal variation of serum C4 levels. Confounding of the fasting serum C4 data interpretation can arise because of hypertriglyceridemia, alcohol intake and liver disease.