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HelpTest Code FACT Filamentous-Actin (F-actin) Antibody, IgG, Serum
Reporting Name
F-Actin Ab, IgG, SUseful 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.
Performing Laboratory
Mayo Clinic Laboratories in Rochester
Specimen Type
SerumSpecimen 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 Minimum Volume
0.4 mL
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Serum | Refrigerated (preferred) | 21 days | |
| Frozen | 21 days |
Reference Values
Negative: <20.0 U
Weak Positive: 20.0-30.0 U
Positive: >30.0 U
Day(s) Performed
Monday
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 |
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.
Clinical Reference
1. European Association for the Study of the Liver. EASL clinical practice guidelines: autoimmune hepatitis. J Hepatol. 2015;63(4):971-1004
2. Mieli-Vergani G, Vergani D, Czaja AJ, et al. Autoimmune hepatitis. Nat Rev Dis Primers. 2018;4:18017
3. Sebode M, Weiler-Normann C, Liwinski T, Schramm C. Autoantibodies in autoimmune liver disease-clinical and diagnostic relevance. Front Immunol. 2018;9:609
4. Terziroli Beretta-Piccoli B, Mieli-Vergani G, Vergani D. Autoimmune hepatitis: serum autoantibodies in clinical practice. Clin Rev Allergy Immunol. 2022;63(2):124-137
5. Bogdanos DP, Invernizzi P, Mackay IR, Vergani D. Autoimmune liver serology: current diagnostic and clinical challenges. World J Gastroenterol. 2008;14(21):3374-3387
6. Muratori P, Granito A, Pappas G, et al. The serological profile of the autoimmune hepatitis/primary biliary cirrhosis overlap syndrome. Am J Gastroenterol. 2009;104(6):1420-1425.
Report Available
2 to 8 daysMethod Name
Enzyme-Linked Immunosorbent Assay (ELISA)
Testing Algorithm
For more information see First-Line Screening for Autoimmune Liver Disease Algorithm.