Laboratory tests to detect hepatitis C viral infections can be difficult to interpret. The enzyme immunoassay (EIA) for antibodies HCV is done as a screening test, with RIBA or NAT testing done to clarify the results. The authors are from the Centers for Disease Control and Prevention.
Tests used routinely for diagnosis:
(1) enzyme immunoassay (EIA) for antibody to HCV (anti-HCV)
(2) recombinant immoblot assay (RIBA), third generation
(3) nucleic acid test (NAT) for RNA
|
EIA |
RIBA |
NAT |
Pattern |
|
negative |
NA |
NA |
A |
|
positive, low S/C ratio |
NA |
NA |
J |
|
positive, high S/C ratio |
NA |
NA |
B |
|
positive |
negative |
NA |
D |
|
positive |
indeterminate |
NA |
E |
|
positive |
positive |
NA |
C |
|
positive |
NA |
positive |
F |
|
positive |
negative |
negative |
H |
|
positive |
indeterminate |
negative |
I |
|
positive |
positive |
negative |
G |
where:
• Pattern K indicates none of the above patterns.
|
Pattern |
Interpretation |
Comment |
|
A |
anti-HCV negative |
not infected with HCV, unless recent |
|
J |
anti-HCV indeterminate |
additional testing needed |
|
B |
probably anti-HCV positive |
probable HCV infection, few false positive |
|
D |
ant-HCV negative |
not infected with HCV, unless recent |
|
E |
anti-HCV indeterminate |
additional testing needed, draw new specimen |
|
C |
anti-HCV positive |
past or present HCV infection |
|
F |
anti-HCV positive, HCV RNA positive |
active HCV infection |
|
H |
anti-HCV negative HCV RNA negative |
not infected with HCV |
|
I |
anti-HCV indeterminate, HCV RNA negative |
negative for HCV, false positive anti-HCV |
|
G |
anti-HCV positive, HCV RNA negative |
past or present HCV infection, repeat NAT |
|
K |
unexpected result |
repeat testing |
If recent infection is expected, then repeat testing in > 1 month.
For a positive anti-HCV with low S/C ratio, perform RIBA or NAT testing. For positive anti-HCV with high S/C ratio, most represent HCV; however, NAT testing may be done if a false positive is suspected.
Repeat testing with a new specimen should be > 1 month after the first.
Purpose: To interpret diagnostic tests for hepatitis C virus (HCV).
Specialty: Infectious Diseases, Gastroenterology
Objective: laboratory tests, criteria for diagnosis
ICD-10: B17.1, B18.2,
