7AlphaC4




Test Mnemonic

7ALPC4

CPT Codes

  • 82542 - QTY (1)

Aliases

  • 7AC4
  • bile acid diarrhea

Includes

  • 7AlphaC4

Performing Laboratory

LabCorp

FDA Category

Laboratory Developed Test


Specimen Requirements

Volume Type Container Collect Temperature Transport Temperature Special Instructions
0.5 mLSerumSST (Gold) FrozenCollect 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 mLSerumNo additive (Red) FrozenCollect prior to 9am after overnight fast. Separate serum from cells within 2 hours of collection and transfer to standard aliquot tube.
0.5 mLPlasmaEDTA (Lavender) FrozenCollect prior to 9am after overnight fast. Separate plasma from cells within 2 hours of collection and transfer to standard aliquot tube.
0.5 mLPlasmaSodium or Lithium heparin (Green) FrozenCollect 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
FrozenAfter separation from cells: 9 days
RefrigeratedAfter separation from cells: 9 days
AmbientAfter 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.