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Test Code FACT Filamentous-Actin (F-actin) Antibody, IgG, Serum

Reporting Name

F-Actin Ab, IgG, S

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Useful For

Evaluation of patients with hepatitis of unknown origin associated with hypergammaglobulinemia and/or abnormal liver enzymes

 

This test may also be useful for confirming positivity for smooth muscle antibodies.

Method Name

Enzyme-Linked Immunosorbent Assay (ELISA)


Specimen Required


Supplies: Sarstedt Aliquot Tube, 5 mL (T914)

Collection Container/Tube:

Preferred: Serum gel

Acceptable: Red top

Submission Container/Tube: Plastic vial

Specimen Volume: 0.5 mL

Collection Instructions: Centrifuge and aliquot serum into a plastic vial.


Specimen Type

Serum

Specimen Minimum Volume

0.4 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Serum Refrigerated (preferred) 21 days
  Frozen  21 days

Reject Due To

Gross hemolysis OK
Gross lipemia OK
Gross icterus OK
Heat treated specimens Reject

Reference Values

Negative: <20.0 U

Weak Positive: 20.0-30.0 U

Positive: >30.0 U

Interpretation

Positivity for anti-filamentous-actin (F-actin) antibodies may help support a diagnosis of autoimmune hepatitis (AIH) following exclusion of other causes of hepatitis.

 

A negative result for anti-F-actin antibodies does not exclude a diagnosis of AIH.

 

In a study conducted at Mayo Clinic, the F-actin enzyme-linked immunosorbent assay (ELISA) had a clinical sensitivity of 92.9% when using the manufacturer's recommended cutoff of 20.0 U. In addition, the F-actin ELISA had a clinical specificity of 76.7% when using the aforementioned cutoffs. See Supportive Data.

Day(s) Performed

Monday

Report Available

2 to 8 days

Test Classification

This test has been cleared, approved, or is exempt by the US Food and Drug Administration and is used per manufacturer's instructions. Performance characteristics were verified by Mayo Clinic in a manner consistent with CLIA requirements.

CPT Code Information

83516

LOINC Code Information

Test ID Test Order Name Order LOINC Value
FACT F-Actin Ab, IgG, S 44706-0

 

Result ID Test Result Name Result LOINC Value
FACT F-Actin Ab, IgG, S 44706-0

Testing Algorithm

For more information see First-Line Screening for Autoimmune Liver Disease Algorithm.