The sections below summarize the use and interpretation of some of the major tests available for viral hepatitis diagnosis and management.

HAV

Clinical indications for HAV testing include flu-like symptoms and either jaundice or an alanine aminotransferase (ALT) level >200 IU/L (test code 823, Appendix).6 HAV IgM antibody (test code 512, Table 2) is the recommended test for diagnosis of acute HAV infection because it rises early (5-10 days before onset of symptoms) and persists for about 6 months.6,15,16 On the other hand, HAV IgG antibody titer rises later in the course of infection and can persist for a lifetime.15,16 An HAV total antibody test (test code 508) detects both IgG and IgM isotypes; when used in combination with the HAV IgM antibody test (test code 36504), it is an effective way to determine current or previous infection and test for immunity before vaccination.15,16 Follow-up testing in patients with acute HAV infection focuses on evaluation of liver function and monitoring infection for resolution.

Table 2. Tests Available for Diagnosis of HAV Infection [return to contents]

Test code	Test name	Clinical use
512	Hepatitis A IgM Antibody	Indicate acute HAV infection
508	Hepatitis A Antibody, Total	Indicate prior or acute infection with, or immunization to, HAV
36504	Hepatitis A Antibody, Total With Reflex to IgMa	Differentiate acute HAV infection from prior infection with, or immunization to, HAV

HAV, hepatitis A virus.
a	Reflex tests are performed at an additional charge and are associated with additional CPT® codes.

 

Positive HAV IgM antibody test results indicate that the patient has a current or recent HAV infection or recent vaccination (Figure 1). Negative results most likely indicate absence of infection. The presence of HAV total antibody in the absence of HAV IgM indicates previous infection or immunity against HAV infection.

HBV

Laboratory testing assists with patient care through HBV screening, diagnosis, and management (Table 3), as discussed below.

Table 3. Tests Available for Screening, Diagnosis, and Management of HBV Infection [return to contents]

Test code	Test name	Clinical use
39170	HBV Triple Screen Panel With Reflexesa,b Includes HBsAg with reflex confirmation, HBcAb total with reflex to IgM, and HBsAb, quantitative.	Screen for current (acute or chronic) or past HBV infection, or immunity from past resolved infection or vaccination
4848	Hepatitis B Core Antibody (IgM)	First-line diagnostic test for acute HBV infection Indicate recent infection (within preceding 4-6 months)
501	Hepatitis B Core Antibody, Total	Indicate current or prior infection
37676	Hepatitis B Core Antibody, Total, With Reflex to IgMa	Indicate current or prior infection; differentiate recent infection (within preceding 4-6 months) from chronic or prior infection
7105	Hepatitis B Immunity Panelb Includes HBcAb, total and HBsAb, qualitative.	Indicate immunity to HBV
499	Hepatitis B Surface Antibody, Qualitative	Indicate an immune response to HBV from prior infection or vaccination; indicate resolution of HBV infection
8475	Hepatitis B Surface Antibody Immunity, Quantitative	Indicate immunity post-infection, vaccination, or HBIG administration
34000	Hepatitis B Surface Antibody Level, Pre/Post HBIG Infusion	Assess HBV immunoglobulin pre- and post-infusion of HBIG
498	Hepatitis B Surface Antigen With Reflex Confirmationa	Indicate that a person has HBV infection and is infectious Indicates chronic hepatitis B when still positive 6 months after diagnosis of HBV infection
94333	Hepatitis B Surface Antigen, Quantitative, Monitoring (Not for Diagnosis)	Monitor response to therapy
16694	Hepatitis B Virus DNA, Quantitative, PCR With Reflex to HBV, Genotypea,c	Determine need to treat chronic HBV infection Predict likelihood of response to therapy Identify HBV genotype (A–H) for epidemiologic and prognostic purposes Detect HBV mutations associated with resistance to antiviral agents Detect precore and basal core promoter mutations, which may influence outcome
8369	Hepatitis B Virus DNA, Quantitative, Real-Time PCRc	Determine need to treat chronic HBV infection Monitor response to therapy
10529	Hepatitis B Virus Drug Resistance, Genotype, and BCP/Precore Mutationsd	Predict likelihood of response to therapy Identify HBV genotype (A–H) for epidemiologic and prognostic purposes Detect HBV mutations associated with resistance to antiviral agents Detect precore and basal core promoter mutations, which may influence outcome
556	Hepatitis Be Antibody	Indicate convalescence/treatment response
555	Hepatitis Be Antigen	Indicate active viral replication and high infectivity
27	Hepatitis Be Panelb Includes HBeAg and HBeAb.	Indicate response to therapy and level of infectivity (disappearance of HBeAg and appearance of HBeAb)

BCP, basal core promoter; HBcAb, hepatitis B core antibody; HBeAb, hepatitis B e antibody; HBeAg, hepatitis B e antigen; HBIG, hepatitis B immune globulin; HBsAb, hepatitis B surface antibody; HBsAg, hepatitis B surface antigen; HBV, hepatitis B virus; PCR, polymerase chain reaction; peg-IFN, pegylated-interferon.
a	Reflex tests are performed at an additional charge and are associated with additional CPT code(s).
b	Components of panels may be ordered separately.
c	The analytical performance characteristics of this assay have been determined by Quest. The modifications have not been cleared or approved by the US Food and Drug Administration. This assay has been validated pursuant to the CLIA regulations and is used for clinical purposes.
d	This test was developed and its analytical performance characteristics have been determined by Quest. It has not been cleared or approved by the US Food and Drug Administration. This assay has been validated pursuant to the CLIA regulations and is used for clinical purposes.

 

Screening for HBV infection

Prior guidelines recommended screening for HBV infection only in individuals with elevated risk,9,10 but the Centers for Disease Control and Prevention (CDC) now recommends screening all adults aged 18 years and older at least once during their lifetime.8 CDC and others still recommend risk-based screening for individuals of any age with elevated risk for HBV infection (Table 1).8–10

Screening asymptomatic individuals involves testing for hepatitis B surface antigen (HBsAg), hepatitis B surface antibody (HBsAb), and total hepatitis B core antibody (HBcAb), typically performed as a triple panel.8 Quest offers this testing as a triple screen panel (test code 39170) that detects current and past HBV infection and immunity to HBV. Triple screen panel components—HBsAg with reflex confirmation (test code 498), quantitative HBsAb (test code 8475), and HBcAb total with reflex to IgM (test code 37676)—are also offered separately from the triple screen panel (Table 3). An HBV immunity panel (test code 7105) is also offered for screening asymptomatic individuals for immunity due to infection or vaccination using qualitative HBsAb testing.

CDC and USPSTF also recommend HBV screening for all pregnant individuals during each pregnancy.8,18 However, pregnant individuals who have previously received triple panel screening without subsequent risk of HBV exposure only require HBsAg screening (test code 498).8

Periodic screening is recommended for those with ongoing risk.8,9 For periodic screening, the triple panel or alternative testing approaches recommended by the American Association for the Study of Liver Disease (AASLD) may be used (eg, HBcAb [test code 501] followed by HBsAg [test code 498] and HBsAb [test code 499], if positive).8,10

Positive HBsAg indicates either acute or chronic HBV infection, whereas positive HBsAb indicates immunity either from vaccination or a previous, resolved infection (Table 4). Negative results from both HBsAg and HBsAb tests most likely indicate susceptibility to HBV infection. However, these negative results can also occur during the window phase of acute infection (before HBsAb appears) and among individuals with resolved HBV infection whose HBsAb titers have become undetectable.10

Table 4. Interpretation of Hepatitis B Markers [return to contents]

Marker	HBV infection status8,10,16
	Susceptible to infection	Immunity due to vaccination	Immunity due to past infection	Acute	Chronic
HBsAg	–	–	–	+	+
HBsAb	–	+a	+a	–	–
HBcAb, total	–	–	+	+	+
HBcAb, IgM	–	–	–	+	–

+, detected; –, not detected.
HBcAb, hepatitis B core antibody; HBsAb, hepatitis B surface antibody; HBsAg, hepatitis B surface antigen; HBV, hepatitis B virus.
a	Immunity requires ≥10 mIU/mL of HBsAb.

 

Total HBcAb test results help (1) detect HBV infection during the window phase of acute infection, (2) differentiate immunity due to vaccination from immunity due to prior infection, and (3) confirm susceptibility among individuals with negative HBsAg and HBsAb results (Table 4).10 For screening using the Quest triple screen panel, reflex testing for hepatitis B core IgM antibody (HBcAb IgM) is performed if total HBcAb is positive; HBcAb IgM differentiates acute (or recent) infection from chronic infection.16

Diagnosis of acute HBV infection

Clinical criteria for acute HBV infection include a discrete onset of flu-like symptoms and either jaundice or an ALT level >100 U/L.2 Tests for HBsAg (test code 498) and HBcAb IgM (test code 4848) are used to diagnose acute HBV infection in symptomatic individuals because (1) both of these markers are present in acute infections, and (2) HBcAb IgM differentiates acute and chronic infections, since it is only present for about 6 months after infection (Figure 1 and Table 4).2,16

Based on the 6-month definition of chronic HBV infection,2,10,16 individuals with acute HBV infection should be retested for markers of active HBV infection 6 months after initial diagnosis to document resolution or transition to chronic infection (Figure 1). Treatment for acute HBV infection is not usually indicated unless patients have acute liver failure or a severe infection.8,10

Diagnosis of chronic HBV infection

Chronic HBV infection is typically indicated by either a positive result for HBsAg (test code 498) accompanied by a negative result for HBcAb IgM (test code 4848), or 2 positive results for HBsAg that are at least 6 months apart (Figure 1).10,16 Patients testing positive for HBsAg who have likely or confirmed chronic HBV infection should receive an evaluation that includes hepatitis B e antigen (HBeAg, test code 555), hepatitis B e antibody (HBeAb, test code 556 or test code 27 for HBeAg and HBeAb panel), and HBV DNA (test code 8369). Additional recommended testing for these patients includes complete blood count (CBC, test code 6399), comprehensive metabolic panel (test code 10231), and international normalized ratio (INR, test code 8847) (Appendix) and serologic tests for co-infections with other hepatitis viruses and sexually transmitted infections.8,19 Test results inform management of chronic HBV infection, as discussed below.

Chronic HBV infection can also be indicated by a positive HBV DNA or HBeAg result with a negative HBcAb IgM result, or 2 positive results for HBV DNA or HBeAg that are at least 6 months apart.2 HBV DNA and HBeAg are markers of current HBV infection, with HBeAg indicating active viral replication, but these markers are not commonly used for initial diagnosis.16

Monitoring and treatment initiation for chronic HBV

Therapy for chronic HBV infection is focused on minimizing illness and death. For patients without cirrhosis, the decision to treat is based on the phase of the disease (Table 5), HBeAg status (test code 555), serial monitoring of ALT (test code 823) and HBV DNA (test code 8369) levels, liver histology, and other patient-specific factors (eg, age) (Table 6).10 In general, guidelines from AASLD recommend antiviral therapy for patients in the active phases of infection (immune-active and reactivation) when ALT and HBV DNA levels are elevated.10 Results from these tests also define other events during the course of viral hepatitis, including hepatitis flare (≥3-fold increase in ALT over baseline and >100 U/L) and virological breakthrough (>1 log increase in HBV DNA over lowest value during treatment).10

Table 5. Phases of Chronic HBV Infection [return to contents]

Phase10	Criteria
	HBsAg	HBeAg	ALT	HBV DNA	Liver histology
Immune-tolerant	+	+	Normal	>1 million IU/mL (typically)	Inflammation and fibrosis minimal
Immune-active	+	+ or –	Elevated	>20,000 IU/mL (HBeAg-positive) >2,000 IU/mL (HBeAg-negative)	Moderate to severe necroinflammation with or without fibrosis
Inactive	+	–a	Normal	<2,000 IU/mL	Necroinflammation minimal; fibrosis variable
HBV reactivation plus hepatitis flare	+ or –	+ or –	Elevatedb	HBsAg-positive: ≥2 log increase in HBV DNA compared to baseline, or ≥3 log increase in HBV DNA, if previously undetectable, or ≥4 log increase in HBV DNA, if baseline unknown HBsAg-negative: any detectable HBV DNA HBsAg seroreversion from negative to positive: HBV DNA detection not required	Moderate to severe necroinflammation; fibrosis variable
Resolution	– (after previously +)	–	Normal	Undetectable	Necroinflammation minimal; fibrosis variable

+, detected; –, not detected.
ALT, alanine aminotransferase; HBeAb, hepatitis B e antibody; HBeAg, hepatitis B e antigen; HBsAg, hepatitis B surface antigen; HBV, hepatitis B virus.
a	Criteria for inactive phase also includes HBeAb positivity (test code 556 or test code 27 for HBeAg and HBeAb panel).
b	Elevated such that ALT level meets criteria for a hepatitis flare (≥3-fold increase over baseline and >100 U/L).

 

Table 6. Monitoring and Treatment Initiation for Chronic HBV Infection in Patients Without Cirrhosis [return to contents]

HBeAg	ALTa	HBV DNA, IU/mL	Monitoring and treatment recommendations10
+	≤ULN	≤20,000	Monitor ALT, HBV DNA every 3-6 months, HBeAg every 6-12 months Do not treat
		>20,000
	>ULN, ≤2X ULN	≤20,000	Monitor ALT, HBV DNA every 1-3 months Treat if elevations in HBV DNA, ALT persist, or other factors indicate treatment (eg, cirrhosis, age >40)
		>20,000
	>2X ULN	≤20,000
		>20,000	Treat
–	≤ULN	<2,000	Monitor ALT, HBV DNA every 3-6 months, HBsAg every year Do not treat
		≥2,000	Monitor ALT, HBV DNA every 3 months for 1 year, then every 6 months Do not treat
	>ULN, ≤2X ULN	<2,000	Monitor ALT, HBV DNA more frequently (eg, every 1-3 months) Treat if elevations in ALT persist and HBV DNA ≥2,000 IU/mL, or other factors indicate treatment (eg, cirrhosis, age >40)
		≥2,000
	>2X ULN	<2,000
		≥2,000	Treat

+, detected; –, not detected.
ALT, alanine aminotransferase; HBeAg, hepatitis B e antigen; HBV, hepatitis B virus; ULN, upper limit of normal.
a	For management decisions, an ALT ULN of 35 U/L should be used for men, and 25 U/L for women.10

 

For patients with compensated cirrhosis, AASLD recommends treatment regardless of ALT level if HBV DNA is detected.10 For those with decompensated cirrhosis, AASLD recommends treatment regardless of ALT or HBV DNA levels.10

Therapy selection, monitoring, and discontinuation

The 2 main types of therapy for chronic HBV infection are pegylated-interferon (peg-IFN) and nucleos(t)ide analogs (NAs). Laboratory testing should not be the sole factor used to determine which therapy to use, but it can help identify likelihood of success for some patients. If peg-IFN is being considered, HBV genotyping (test code 10529 or test code 16694 for reflex following HBV DNA) can predict the likelihood of success. Loss of HBeAg and HBsAg is more likely in patients with genotypes A and B compared to those with other genotypes.10 In addition, certain HBV mutations are associated with more severe disease and, together with HBV genotype, may help inform prognosis and predict response to peg-IFN therapy (test code 10529 or 16694).20,21 HBV treatment is an active area of research, so the most recent AASLD guidelines should be consulted for current treatment recommendations.

Therapy selection can also be influenced by the presence of a concurrent infection with HCV, HDV, and/or HIV.

• Concurrent therapy with NAs for HBV and direct-acting antivirals (DAAs) for HCV is recommended for patients coinfected with HBV and HCV who meet criteria for HBV treatment (Table 6).10
• Peg-IFN and NA may be indicated for patients coinfected with HBV and HDV, depending on levels of HBV DNA and HDV RNA.10
• Therapy must be coordinated in HBV and HIV coinfected individuals because many anti-HBV drugs also have anti-HIV activity. The treatment regimen should include 2 drugs with anti-HBV activity.10

Once a patient begins treatment, response to therapy can be measured using a variety of laboratory tests.

• ALT: falling levels during treatment are consistent with treatment response (test code 823).22
• HBeAg and HBeAb: loss of HBeAg (test code 555) in HBeAg-positive patients is an indicator of treatment response.22 As discussed further below, concurrent acquisition of HBeAb (test code 556 or test code 27 for HBeAg and ABeAb panel) may indicate eligibility to discontinue NA treatment, depending on other patient characteristics.10
• HBsAg and HBsAb: loss of HBsAg (test code 498) and the concurrent acquisition of HBsAb (test code 499) indicates resolution of infection. Only 1% of chronic HBV patients per year achieve loss of HBsAg.22 HBsAg loss is associated with better survival rates and lower risk of hepatic decompensation.22
• Quantitative HBsAg: testing can help manage patients receiving peg-IFN therapy (test code 94333).10 HBsAg levels predict response to peg-IFN and help inform whether treatment should be stopped.10,23
• Quantitative HBV DNA: assays help monitor response to therapy and detect the emergence of resistance to antiviral agents (test code 8369). Monitoring of HBV DNA levels is recommended every 3 months until undetectable, then every 3 to 6 months thereafter.10,19 Decreasing HBV DNA levels over time indicate that therapy is working. Conversely, a large increase in HBV DNA levels (virological breakthrough) can indicate the emergence of resistance or medication nonadherence in patients treated with NAs.10 A change in treatment regimen may be appropriate for patients who have virologic breakthrough when being treated with an NA.10
• HBV drug resistance: testing detects the emergence of mutations associated with resistance to antiviral drugs (test code 10529). Testing patients with virologic breakthrough can help guide changes in treatment regimen.10
• Tests to help monitor potential adverse treatment effects: for specific information on tests needed to monitor each therapy, see AASLD guidelines. Tests include CBC (test code 6399), serum creatinine (test code 375), and others.10

Even if a patient responds to therapy, determining the appropriate time to discontinue a therapeutic regimen can be difficult. The preferred duration of peg-IFN therapy is 48 weeks, but the duration of NA therapy depends on the phase of the infection, HBV DNA levels, and the presence or absence of cirrhosis. Thus, testing for HBsAg (test code 498), HBeAg/HBeAb (test code 27), HBV DNA (test code 8369), and ALT (test code 823) can help with the decision to discontinue NA treatment and help monitor patients once treatment stops (Table 7).10

Table 7. Criteria for Discontinuing Nucleos(t)ide Analog Therapy for Chronic HBV Infection [return to contents]

HBeAg	Compensated cirrhosis	Criteria for discontinuing therapy10,a
+ (with seroconversion to HBeAb+ on therapy)	Yes	Indefinite therapy, unless strong rationale for discontinuationb
	No	Discontinue therapy if ALT normal and HBV DNA undetectable for 12 months
–	Yes	Indefinite therapy
	No	Indefinite therapy, unless strong rationale for discontinuationb

+, detected; –, not detected.
ALT, alanine aminotransferase; HBeAb, hepatitis B e antibody; HBeAg, hepatitis B e antigen; HBV, hepatitis B virus.
a	Patients without cirrhosis who discontinue therapy should be monitored every 3 months for at least 1 year for recurrent viremia, hepatitis flares, seroconversion, and clinical decompensation. Patients with cirrhosis who discontinue therapy require more frequent monitoring. Discontinuation of therapy should include consideration of risks and benefits, including virological collapse, hepatic decompensation, liver cancer, death, burden of therapy (eg, financial costs), and preferences of patient or provider.10
b	For example, HBsAg loss.

 

Resolution of chronic HBV infection

The sustained loss of HBsAg, along with undetectable HBV DNA and an absence of clinical or histological evidence of active viral infection, indicates resolution of chronic hepatitis B.10 Routine monitoring of ALT and HBV DNA is no longer necessary, but continued HCC surveillance is recommended for individuals with cirrhosis or other risk factors.10

Vaccination and assessment of immune status

HBV vaccination recommendations are provided by the CDC Advisory Committee on Immunization Practices.11 Postvaccination serologic testing for HBV immunity is important for populations whose immune status informs their subsequent clinical management, such as the need for revaccination or postexposure prophylaxis (ie, HBV vaccination and/or hepatitis B immune globulin [HBIG] injection). Testing for quantitative HBsAb (test code 8475) is used to determine immune status in these scenarios.

Postvaccination testing for HBV immunity is recommended for the following groups11:

• Infants born to HBsAg-positive individuals or those whose HBsAg status is unknown (should also be tested for HBsAg status [test code 498])
• Healthcare and public safety workers
• Hemodialysis patients and patients who might require outpatient hemodialysis
• Individuals with HIV infection
• Immunocompromised individuals
• Sex partners of HBsAg-positive individuals

Individuals with HBsAb levels ≥10 mIU/mL have immune protection. Individuals with HBsAb levels <10 mIU/mL should be revaccinated according to CDC guidelines.11 Annual testing for HBsAb levels to determine the need for booster doses is recommended for hemodialysis patients and can be considered for immunocompromised individuals who have ongoing risk of HBV exposure.11 HBsAb testing before and after receiving postexposure prophylaxis (test code 34000) is available for management of exposed healthcare workers, when indicated.11

HCV

HCV infection can be limited to an acute illness, but it develops into chronic disease in about half of infected individuals.3 This section discusses laboratory testing to support the screening, diagnosis, and treatment of HCV infection (Table 8).

Table 8. Tests Available for Screening, Diagnosis, and Management of HCV Infection [return to contents]

Test code	Test name	Clinical use
94345	Hepatitis C Antibody With Reflex to HCV RNA, PCR With Reflex to Genotypea	Screen for and diagnose HCV infection Establish baseline viral load for treatment monitoring Determine HCV genotype if needed to select the most appropriate treatment
8472	Hepatitis C Antibody With Reflex to HCV, RNA, Quantitative, Real-Time PCRa	Screen for and diagnose HCV infection Establish baseline viral load for treatment monitoring
91704	Hepatitis C-Infected Patient, Baseline Panel 1a,b Includes hepatic function panel, CBC (with differential and platelets), total HAV antibody, total hepatitis B core antibody, qualitative hepatitis B surface antibody, hepatitis B surface antigen with reflex to confirmation, HCV RNA genotype), HIV-1/2 antibodies with reflexes, and serum creatinine with calculated eGFR.	Assess risk from underlying medical conditions and comorbid infections prior to initiation of HCV therapy Determine HCV genotype if needed to select the most appropriate treatment
91707	Hepatitis C-Infected Patient, Baseline Panel 2a,b Includes hepatic function panel, CBC (with differential and platelets), HCV RNA genotype, HIV-1/2 antibodies with reflexes, and serum creatinine with calculated eGFR.	Assess risk from underlying medical conditions and comorbid infections prior to initiation of HCV therapy; does not include hepatitis A or B testing Determine HCV genotype if needed to select the most appropriate treatment
92447	Hepatitis C Viral RNA Genotype 1 NS5A Drug Resistancec	Detect mutations associated with NS5A inhibitor resistance or failure Guide selection of therapy in patients with HCV genotype 1a infection
93325	Hepatitis C Viral RNA Genotype 3 NS5A Drug Resistancec	Detect mutations associated with NS5A inhibitor resistance or failure Guide selection of therapy in patients with HCV genotype 3 infection
37811	Hepatitis C Viral RNA, Genotyped	Guide treatment selection and duration
93871	Hepatitis C Viral RNA Genotype, With Reflex to HCV NS5A Drug Resistancea,d	Determine HCV genotype if needed to select the most appropriate treatment. If genotype is 1, reflex to NS5A drug resistance test (test code 92447)
35645	Hepatitis C Viral RNA, Quantitative, Real-Time PCRd	Confirm active HCV infection and establish baseline viral load Assess response to therapy Test for recurrence or reinfection
11348	Hepatitis C Viral RNA, Quantitative, Real-time PCR With Reflex to Genotypea,d	Confirm active infection and establish baseline viral load. Determine HCV genotype if needed to select the most appropriate treatment Perform only for baseline evaluation. If baseline RNA already measured, order genotype only
93873	Hepatitis C Viral RNA, Quantitative Real-Time PCR With Reflexesa,d Includes reflexes to HCV RNA genotype, and HCV RNA genotype 1 NS5A drug resistance.	Confirms active infection and establishes baseline viral load Determine HCV genotype if needed to select the most appropriate treatment. If genotype is 1, reflex to NS5A drug resistance test (test code 92447)

ALT, alanine aminotransferase; CBC, complete blood count; eGFR, estimated glomerular filtration rate; HAV, hepatitis A virus; HCV, hepatitis C virus; PCR, polymerase chain reaction.
a	Reflex tests are performed at an additional charge and are associated with additional CPT code(s).
b	Components of panels may be ordered separately.
c	This test was developed and its analytical performance characteristics have been determined by Quest. It has not been cleared or approved by the US Food and Drug Administration. This assay has been validated pursuant to the CLIA regulations and is used for clinical purposes.
d	The analytical performance characteristics of this assay have been determined by Quest Diagnostics. The modifications have not been cleared or approved by the US Food and Drug Administration. This assay has been validated pursuant to the CLIA regulations and is used for clinical purposes.

 

Screening and diagnosis for HCV infection

One-time screening for HCV infection is recommended for all individuals 18 years or older.3,13,14 For individuals under 18 years old, 1-time screening is recommended for those who are at risk for HCV infection (Table 1).3,13 Individuals with ongoing risk factors or exposures should continue to be screened periodically, and people who inject drugs, HIV-infected men who have unprotected sex with men, and men who have sex with men taking pre-exposure prophylaxis (PrEP) should be screened annually.3,13,14 Pregnant individuals should be screened during each pregnancy.3,13 Finally, HCV screening is also recommended for any individual who requests it, whether or not they disclose any risk factors.3

Acute HCV infection is often asymptomatic, but potential signs and symptoms include flu-like symptoms or jaundice. An unexplained elevated ALT level should also prompt suspicion for acute infection.13

HCV antibody immunoassays are used as the initial test for screening and diagnosis of HCV infection (Figure 1). However, antibody tests cannot differentiate between current and past infection; an RNA test is needed for that purpose. Reflex HCV RNA tests are used to confirm infection in antibody-positive individuals (test code 8472).14,17,24 Standalone HCV RNA testing (test code 35645) is used to diagnose people at risk of reinfection after previous viral clearance and those with a negative HCV antibody test who were exposed to HCV within the past 6 months.13 Unlike antibody tests, which are not positive until 4 to 10 weeks after infection, RNA tests can detect HCV 1 to 2 weeks after infection.3 An RNA method can also be considered to diagnose HCV infection in immunocompromised individuals.13

Results of antibody and RNA tests can be used together to indicate infection status or history (Figure 1). Additional testing with another HCV antibody assay may be appropriate to differentiate resolved HCV infection from a biologic false-positive antibody test, which is more likely among people at low risk for HCV infection.13,24

Treatment selection

Therapy for chronic HCV infection focuses on eradicating viral infection and preventing complications such as HCC, cirrhosis, and liver failure. Therapy is generally recommended for all patients with active HCV infection, except those with a short life expectancy that would not be improved by treatment.13

Assessing the severity of fibrosis is recommended for all people with HCV infection to guide treatment decisions and follow-up care (Table 9).13 A biopsy is the historic “gold standard” for assessing fibrosis, but the procedure carries a moderate risk of complications and is subject to sampling error. Noninvasive methods, including imaging and serum biomarkers, may be used instead to assess the likelihood of advanced fibrosis.13 Biomarker testing options include the FIB-4 score (test code 30555), FibroTest-ActiTest (test code 92688), Enhanced Liver Fibrosis score (test code 10350), and others (Appendix). The simplified HCV treatment recommendations from AASLD and the Infectious Diseases Society of America (IDSA) include the FIB-4 score during pretreatment assessment, but results from other fibrosis tests may also be used to assess for cirrhosis.13

Table 9. Laboratory Testing Recommended for HCV Antiviral Therapy [return to contents]

Test13,a	Baseline	On-treatment	Post-treatment
Quantitative HCV RNA	●		●
Hepatic function Panelb	●	●c	●d
Complete blood count	●	●e	●d
INR	●	●f	●d,f
Advanced fibrosis evaluation (liver biopsy, imaging, and/or noninvasive markers, such as FIB-4 or FibroTest™)	●
Estimated glomerular filtration rate (eGFR)	●
HBsAg, HBsAb, HBcAb (total)	●
HCV genotype/subtype	●g
HCV resistance-associated substitutions (RASs)	●h		●i
HIV antigen/antibody	●
Serum pregnancy test	●

ALT, alanine aminotransferase; HBcAb, hepatitis B virus core antibody; HBsAb, hepatitis B virus surface antibody; HBsAg, hepatitis B virus surface antigen; HCV, hepatitis C virus; HIV, human immunodeficiency virus; INR, international normalized ratio.
a	Not a complete listing of all recommended pre-, on-, and post-treatment laboratory testing. See AASLD-IDSA HCV guidance for complete recommendations.13
b	Includes levels of albumin, ALT, alkaline phosphatase, aspartate aminotransferase, and bilirubin (direct and total).
c	For patients being treated with elbasvir/grazoprevir (recommended at 8 weeks and, if on a 16-week regimen, 12 weeks), or as clinically indicated (eg, may be appropriate for patients with cirrhosis).13
d	Monitor patients who did not achieve a sustained virologic response until retreatment occurs.13
e	Monitoring for anemia is recommended for patients treated with regimens that include ribavirin.13
f	Recommended for patients taking warfarin.13
g	Only if results would affect treatment decisions (eg, if a non-pan-genotypic therapy is being considered).13
h	Only required for certain combinations of genotypes and direct-acting antiviral therapies.13
i	Recommended for patients who will receive retreatment and for whom results would impact treatment decisions.13

 

Additional testing is recommended before treatment to help select the most appropriate therapy and assess for underlying medical conditions (Table 9).13 Quest offers a baseline panel that includes testing for hepatitis A and B (test code 91704) as well as a panel without hepatitis A or B biomarkers (test code 91707) for patients who have already received such testing. Vaccinations for hepatitis A and B are recommended for patients with HCV infection who are susceptible to those infections.13

Many treatment options are available, including DAAs, peg-IFN, ribavirin, and various combinations. The AASLD/IDSA guidelines provide thorough recommendations about selecting an appropriate therapeutic regimen, including simplified treatment using pan-genotypic DAAs for eligible patients.13 Therapy selection depends mainly on (1) previous treatment status (treatment-naive vs treatment-experienced), (2) cirrhosis status (without vs compensated vs decompensated), (3) other comorbidities and medications, and (4) HCV genotype.13 Patients who are treatment-naive, and not pregnant, and do not have decompensated cirrhosis, end-stage renal disease, HBV infection, HCC, or a liver transplant, are eligible for simplified treatment.13 HCV treatment recommendations change rapidly, so the most recent AASLD/IDSA guidelines should be consulted for current treatment recommendations.13

Given the availability of pan-genotypic DAAs, most patients do not require testing for HCV genotype for treatment selection. HCV genotyping is needed only if it will influence treatment decisions (eg, when treatment with a non-pan-genotypic DAA is being considered).13 HCV genotyping may be ordered as a standalone test (test code 37811) or as reflex testing following RNA detection (test code 11348) or following HCV antibody and RNA detection (test code 94345).

For certain groups of patients with HCV genotypes 1a or 3, testing for resistance-associated substitutions (RASs) in the NS5A protein further guides treatment selection (Table 10).13 Quest offers standalone NS5A RAS testing for genotype 1 (test code 92447) and genotype 3 (test code 93325). Reflex testing following genotype 1 detection (test code 93871) or following HCV RNA and genotype 1 detection (test code 93873) is also available.

Table 10. Indications for NS5A RAS Testing and Interpretations [return to contents]

DAA regimen being considered13	HCV genotype	Treatment experience	Compensated cirrhosis	NS5A RAS result	Impact on DAA regimen
Elbasvir/grazoprevir	1a	TN or TE	Yes or No	Any RAS present	Change regimen
				RASs absent	Proceed with regimen
Ledipasvir/sofosbuvir	1a	TE	Yes or No	Clinically significanta RASs present	Change regimen
				Clinically significanta RASs absent	Proceed with regimen
Sofosbuvir/velpatasvir	3	TN	Yes	Y93H present	Add ribavirin, or change regimen
				Y93H absent	Proceed with regimen
Sofosbuvir/velpatasvir	3	TE	No	Y93H present	Add ribavirin, or change regimen
				Y93H absent	Proceed with regimen

DAA, direct-acting antiviral; HCV, hepatitis C virus; RAS, resistance-associated substitution; TE, treatment-experienced; TN, treatment-naive.
a	Defined as a ≥100-fold shift in in vitro EC50 to ledipasvir.

 

On-treatment monitoring and treatment response

On-treatment monitoring is not necessary for all patients but may be appropriate for certain groups (Table 9). Among patients who have their liver function monitored, guidelines recommend discontinuing therapy for those with a large increase in ALT levels (≥10-fold), or a smaller increase (<10-fold) if associated symptoms are present. Closer monitoring (every 2 weeks) is warranted for those who have smaller increases in ALT levels (<10-fold), but without symptoms.13

Treatment response is primarily assessed by quantitative HCV RNA (test code 35645) and liver function tests (test code 10256) ≥12 weeks after the end of treatment (Figure 2).13 Absence of detectable HCV RNA indicates a sustained virological response (SVR), or cure of HCV infection. If ALT levels are elevated after treatment despite SVR, assessment for other causes of liver disease is recommended and a second HCV RNA test at ≥24 weeks after end of treatment may be considered.13

Failure to achieve SVR indicates treatment failure. CBC, INR, and liver function tests (Appendix) are recommended every 6 to 12 months to monitor disease progression among patients in whom treatment failed.13 Patients can be retreated after treatment failure, and the AASLD HCV guidance provides thorough recommendations for treatment-experienced patients.13 Although the selection of RASs can be responsible for treatment failures, testing for RASs during or after therapy is not recommended unless indicated by patient characteristics and the DAA regimen being considered for retreatment (Table 10).13

Resolution of chronic HCV infection

Resolution of HCV infection is indicated by SVR ≥12 weeks after treatment. Patients without cirrhosis are recommended to resume standard medical care, with assessment for recurrence using an HCV RNA test (test code 35645) only if unexplained hepatic dysfunction occurs. Annual screening is recommended if the patient remains at risk for HCV infection.13 For patients with cirrhosis, HCC and upper endoscopic surveillance is recommended.13

HDV

HDV infection occurs only in the context of active HBV infection. AASLD recommends HDV screening for HBsAg-positive individuals who are at higher risk for HDV infection, but more recent guidance from the Chronic Liver Disease Foundation (CLDF) recommends universal screening of all HBsAg-positive individuals.5,10 Laboratory testing is used for screening, diagnosis, differentiating acute coinfection from superinfection, and determining if the HDV infection is active or resolved (Table 11, Figure 3). The total HDV antibody assay is recommended as the initial test.5,10,25

• Positive total HDV antibody results, in the presence of HBsAg, indicate past or current HDV infection.
• Negative total HDV antibody results are consistent with the absence of HDV infection. However, because HDV antibodies generally appear late in acute infection, false-negative results are possible.

Table 11. Tests Available for Screening, Diagnosis, and Management of HDV Infection [return to contents]

Test code	Test name	Clinical use
4848	Hepatitis B Core Antibody (IgM)	Differentiate HBV/HDV coinfection and superinfection
4990	Hepatitis D Virus (HDV) Antibody, Totala	Screen for HDV infection; indicates past or current infection
37231	Hepatitis D Virus (HDV) Antibody, Total With Reflex to HDV, Real-Time PCRa,b	Screen for and diagnose HDV infection; presence of HDV RNA indicates active infection
35664	Hepatitis D Virus (HDV) Antibody (IgM)a	Indicates active HDV infection
37027	Hepatitis D Virus Antibodies (Total, IgM)a Includes HDV antibody, total and HDV antibody IgM.	Screen and aid in the diagnosis of HDV infection
34469	Hepatitis D Virus RNA, Qualitative, Real-Time PCRa	Confirm HDV infection in individuals with reactive HDV antibody results Test for resolution
37889	Hepatitis D Virus RNA, Quantitative Real-Time PCRa	Confirm HDV infection in individuals with reactive HDV antibody results Guide treatment selection Test for resolution

HBV, hepatitis B virus; HDV, hepatitis D virus; PCR, polymerase chain reaction.
a	This test was developed and its analytical performance characteristics have been determined by Quest. It has not been cleared or approved by the US Food and Drug Administration. This assay has been validated pursuant to the CLIA regulations and is used for clinical purposes.
a	Reflex tests are performed at an additional charge and are associated with additional CPT codes.

 

Positive HDV antibody results should be followed by HDV RNA testing to confirm active infection.5,10,25 CLDF recommends reflex testing using a quantitative HDV RNA assay (test code 37231).5 Quest also offers qualitative (test code 34469) and quantitative (test code 37889) HDV RNA testing that can be ordered separately from the total HDV antibody test (test code 4990).

• Positive results or detectable HDV RNA in patients with HDV antibodies indicates active infection, whereas negative results or undetectable HDV RNA indicates resolved infection.
• HDV IgM antibody (test code 35664 and included in test code 37027) is an alternative marker of active HDV infection and HDV replication. This testing was more common when HDV RNA testing was less available.25

For patients with active HDV infection, prognosis and management depend on the type of infection.5 HBcAb IgM testing (test code 4848) can be used to help differentiate coinfection and superinfection.5,25 HBcAb IgM is a marker of acute HBV infection, which is usually associated with coinfection. Thus, those positive for HBcAb IgM are likely to have HDV/HBV coinfection, while those negative for HBcAb IgM are likely to have HBV/HDV superinfection (Figure 3).5

HDV RNA (quantitative) (test code 37889), HBV DNA (test code 8369), and liver function tests are used to help manage HDV infections. Periodic monitoring of HDV RNA and HBV DNA levels is recommended for patients with HDV infection, as results of these tests help guide treatment decisions.5,10 AASLD defines successful treatment of HDV infection as a lack of detectable HDV RNA 24 weeks after completion of therapy, though relapses are common.10 Following treatment for HDV, HDV RNA testing can help assess patients with elevated ALT levels for relapse.10

 

Appendix [return to contents]

Additional Laboratory Tests for Diagnosis and Management of Viral Hepatitis

Test code	Test name	Clinical use
823	Alanine Aminotransferase (ALT)	Diagnose and manage certain liver diseases (eg, viral hepatitis, cirrhosis)
6399	CBC (includes Differential and Platelets)	Assess risk from underlying medical conditions or adverse treatment effects prior to, during, and/or after treatment for HBV or HCV
10231	Comprehensive Metabolic Panel Includes albumin (test code 223), albumin/globulin ratio (calculated), alkaline phosphatase (test code 234), ALT (test code 823), AST (test code 822), BUN (test code 294), BUN/creatinine ratio (calculated), calcium (test code 303), carbon dioxide (test code 310), chloride (test code 330), creatinine (test code 375), globulin (calculated), glucose (test code 483), potassium (test code 733), sodium (test code 836), total bilirubin (test code 287), and total protein (test code 754).	Assess risk from underlying medical conditions prior to initiation of HBV therapy
375	Creatinine Includes serum creatinine and eGFR calculation.	Assess risk from underlying medical conditions or adverse treatment effects prior to, during, and/or after treatment for HBV or HCV
10350	Enhanced Liver Fibrosis (ELF) Score	Assess the likelihood of advanced fibrosis in patients with HCV infection
8396	hCG, Total, Quantitative	Determine if patient is pregnant prior to initiation of HCV therapy (serum specimen)
10256	Hepatic Function Panela Includes total protein (test code 754), albumin (test code 223), globulin (calculated), albumin/globulin ratio (calculated), total bilirubin (test code 287), direct bilirubin (test code 285), indirect bilirubin (calculated), alkaline phosphatase (test code 234), AST (test code 822), ALT (test code 823).	Assess liver function prior to, during, and after treatment for HCV
6462	Hepatitis Panel, Generala,b Includes total HAV Ab, qualitative HBsAb, HBsAg w/rfl confirmation, total HBcAb, HCV Ab w/rfl HCV RNA.	Assess for immunity or infection from HAV, HBV, or HCV
91431	HIV-1/2 Antigen and Antibodies, Fourth Generation, With Reflexesb	Diagnose underlying HIV-1/2 infection
30555	Liver Fibrosis, Fibrosis-4 (FIB-4) Index Panel	Assess the likelihood of advanced fibrosis in patients with HCV infection
92688	Liver Fibrosis, FibroTest-ActiTest Panelc Includes alpha-2-macroglobulin (test code 228), ALT (test code 823), apolipoprotein A1 (test code 5223), fibrosis score/stage/interpretation, gamma glutamyl transferase (GGT) (test code 482), haptoglobin (test code 502), necroinflammation activity score/grade/interpretation, and total bilirubin (test code 287).	Assess the likelihood of advanced fibrosis in patients with HCV infection
8847	Prothrombin Time with INR	Assess risk from underlying medical conditions or adverse treatment effects prior to, during, and/or after treatment for HBV or HCV

ALT, alanine aminotransferase; AST, aspartate aminotransferase; BUN, blood urea nitrogen; CBC, complete blood count; HAV, hepatitis A virus; HBcAb, hepatitis B core antibody; HBsAb, hepatitis B surface antibody; HBsAg, hepatitis B surface antigen; HBV, hepatitis B virus; hCG, human chorionic gonadotropin; HCV, hepatitis C virus; INR, international normalized ratio. Refer to the Quest Diagnostics Test Directory (QuestDiagnostics.com/TestDirectory) for additional testing options.
a	Components of panels may be ordered separately.
b	Reflex tests are performed at an additional charge and are associated with additional CPT codes.
c	This test was developed and its analytical performance characteristics have been determined by Quest. It has not been cleared or approved by the US Food and Drug Administration. This assay has been validated pursuant to the CLIA regulations and is used for clinical purposes.