Diagnostic tests for hepatitis

Diagnosis


Hepatitis C

Testing for hepatitis C

Hepatitis C is usually diagnosed using 2 blood tests: the antibody test and the PCR test. The results usually come back within 2 weeks.

The antibody test

The antibody blood test determines whether you have ever been exposed to the hepatitis C virus by testing for the presence of antibodies to the virus. Antibodies are produced by your immune system to fight germs.

The test will not show a positive reaction for some months after infection because your body takes time to make these antibodies.

If the test is negative, but you have symptoms or you may have been exposed to hepatitis C, you may be advised to have the test again.

A positive test indicates that you have been infected at some stage. It doesn’t necessarily mean you are currently infected, as you may have since cleared the virus from your body.

The only way to tell if you are currently infected is to have a second blood test, called a PCR test.

The PCR test

The PCR blood test checks if the virus is still present by detecting whether it is reproducing inside your body.

A positive test means your body has not fought off the virus and the infection has progressed to a long-term (chronic) stage.

Diagnosing Hepatitis: Tools and New Tests

Finding out about hepatitis is getting quicker and easier.

Liver inflammation, otherwise known as hepatitis, can result from infection with various types of viruses. Because different hepatitis viruses cause similar symptoms, it’s impossible to tell which virus is behind the problem without running a series of diagnostic tests.

Evaluating Liver Function

If your doctor suspects you have hepatitis, she might order a series of hepatitis tests that focus on your liver. Your liver produces proteins, enzymes, and other substances that aid in digestion, help clear toxins from your body, and turn food into energy. A liver function blood-test panel will tell your doctor how well your liver is performing these important jobs.

For liver function tests (LFTs), a sample of your blood will be taken and analyzed. (Not all of these tests strictly measure liver function, but this terminology is still often used.) To get the most accurate results, you might have to fast for 10 to 12 hours before the test. Abnormalities in the levels of the following substances may suggest that you have hepatitis:

  • Albumin. One of the liver’s jobs is to make albumin, a protein that helps move minerals and nutrients through the bloodstream. Low albumin can be a sign of liver disease.
  • ALP, ALT, AST. These enzymes assist with bone growth, process proteins, and convert food into energy, respectively. High levels may signal hepatitis.
  • Bilirubin. This is the pigment that is produced when red blood cells break down. If your liver is not working well due to hepatitis, bilirubin can cause jaundice (yellowing of the skin and the whites of the eyes); your bilirubin level will also show up as elevated in a blood test.

Viral Serology or Hepatitis Panel

Your doctor may order a viral serology panel, a group of blood tests that determines whether you have hepatitis, which strain it is, and the severity of your illness. A sample of blood is taken from the arm or hand and used to do a screening test for all types of the virus. At the lab, the technician checks the sample for specific markers of the viruses that may have invaded your body, as well as the specific antibodies that your immune system will have produced to fight them off.

Typically blood is tested for:

  • Hepatitis A antigen
  • An antibody against hepatitis A
  • Hepatitis B antigens (surface and core antigens)
  • An antibody against hepatitis B (surface antigen and e-antigen)
  • An antibody against hepatitis C
  • The presence of a newly made antibody (called IgM antibody, which, if present, means that you just recently became infected), as well as an antibody from prior exposure to a virus or a vaccine (IgG antibody)

These tests are also used in long-term management of hepatitis, to keep track of how your treatment is progressing. As the infection clears, the presence of an antigen from the virus will disappear. If the infection smolders and becomes chronic, there will continue to be an antigen or antigens in the blood.

DNA Test for Hepatitis B

DNA is the genetic material or blueprint of the hepatitis B virus, or HBV. An HBV DNA test can be done to measure how much of this genetic material you have in your body. How much you have indicates how rapidly the virus is making copies of itself in your liver.

  • Low levels (less than 300 copies per milliliter or one drop of blood) suggest the virus is inactive.
  • High levels (from 100,000 to a billion or more) indicate the virus is active and rapidly replicating itself. HBV DNA levels can go up and down and only indicate your viral load at the time the test is performed.

Rapid Tests for Hepatitis C

In 2010, the Food and Drug Administration approved a rapid antibody test for detecting hepatitis C antibodies. The test can be done with blood from a finger stick, and reliable results are available within 20 minutes. The test is for those 15 years and older who are at risk for infection with the hepatitis C virus (HCV) and for those with signs and symptoms of hepatitis C.

Hepatitis C RNA Testing

Hepatitis C RNA qualitative is a molecular test that tells whether the hepatitis C virus is present in your bloodstream. A qualitative (yes or no) test is more accurate than a quantitative test, which measures the amount of virus present. A qualitative test is able to detect very low levels of the virus. This test is often used for screening and to determine whether treatment is working.

Liver Biopsy

In some cases, your doctor may need to examine a liver tissue sample, especially with advanced disease. The sample is taken in a process called a liver biopsy. You will either be sedated or given a local anesthetic, and a tiny sample of liver tissue will be removed with a long needle through a small incision on your right side.

If you have chronic hepatitis B and C, a biopsy can determine the stage and severity of disease. A liver biopsy can also be used to diagnose some of the complications of advanced hepatitis including fibrosis, cirrhosis, and liver cancer.

A liver biopsy is not without risk. Dangerous bleeding can sometimes occur, as well as infection. There is now a trend to use less invasive methods of diagnosing liver tissue damage from chronic hepatitis (see elastography below).

Other Diagnostic Tools

Other tests for advanced disease include checking your liver for signs of fibrosis (stiffening from scarring), which can tell your doctor how far along your hepatitis has progressed. These include:

  • Paracentesis. Fluid from your abdomen can be tested to help differentiate among the many possible causes of liver disease. During this test, a doctor will remove the fluid through a needle.
  • Elastography. This non-invasive test is a means of checking for fibrosis and uses sound waves to measure the liver’s stiffness. Elastography tests are most accurate in identifying advanced disease.
  • Surrogate markers. These are panels of blood tests that look for abnormal levels of certain substances in the blood (surrogate markers) that seem to parallel the development of fibrosis and cirrhosis. These markers are different than the usual blood tests done to diagnose hepatitis.

When diagnosing hepatitis, a combination of tests may be necessary to determine the type of hepatitis you have, how much it has progressed, and ultimately to decide on the best course of treatment for your condition.

Viral Hepatitis 

  • The 5 identified forms of viral hepatitis affect about 400 million people worldwide.
  • The viral hepatitis pandemic is responsible for an estimated 1.4 million deaths per year. 47% are attributable to hepatitis B virus and 48% to hepatitis C virus.
  • Viral hepatitis A and E are food- and water-borne infections that can result in acute outbreaks in communities with unsafe water and poor sanitation.
  • More than 95% of people living with chronic hepatitis don’t know they have it.
  • In 2015, less than 1% of people with chronic hepatitis infection were receiving treatment.

Sources:

  • Global health sector strategy on viral hepatitis 2016-2021
  • WHO factsheets

Definition

Hepatitis is an inflammation of the liver. Acute infection of some types of hepatitis can lead to chronic infection, potentially causing liver diseases including cirrhosis and cancer. It can be developed as a result of alcoholism or medications, but is most commonly caused by viral infection. Five distinct hepatitis viruses have been identified: A, B, C, D and E. Together they affect about 400 million people worldwide. Hepatitis A, B, and C are the most commons types.

Hepatitis B and C, which can lead to chronic hepatitis, are particularly prevalent. They are leading causes of liver cancer, liver cirrhosis and mortality1,2,3. Cirrhosis due to hepatitis is one of the main reasons for liver transplants2.

The means of transmission differs according to the type of viral hepatitis (see chart). Vaccines are available for HAV and HBV; otherwise hygiene and education contribute to prevention. During the acute phase, hepatitis may cause “flu-like” symptoms (e.g. nausea, vomiting), jaundice, white stools, and dark urine. Yet viral hepatitis is largely asymptomatic nature, so most people don’t know they are affected. That’s why viral hepatitis is called a “silent epidemic”.

Means of potential viral hepatitis transmission

Means

HAV

HBV

HCV

HDV

HEV

Food and water contamination most common no no HDV infection is linked to HBV infection. most common
Blood e.g. through transfusion; contaminated instruments in healthcare settings; sharing needles among drug users no yes yes rare
Sex with an infected person rare yes yes rare
Mother-to-child transmission rare yes yes rare

Diagnosis

Hepatitis can be difficult to diagnose because it can be asymptomatic or symptoms may be non-specific.

  • Non-specific or absent symptoms (90% of cases):
    • pain in right hypochondrium – fever
    • nausea and vomiting – arthralgia
    • urticaria
  • Specific symptom (≤ 10% of cases)4:
    • icterus (jaundice)
  • Severe form: fulminant hepatitis
    • clinical signs: hepatic encephalopathy
    • biological signs: prothrombin level (< 50%) ; transaminase level not correlated with the severity of fulminant hepatitis

When a patient is suspected to have hepatitis knowing their background often helps clinicians orient their diagnosis.1,2 People at higher risk include:

  • HIV-infected individuals are at higher risk of both hepatitis B and C. An estimated ¼ of HIV-infected people in the US are also HCV-infected2
  • Men who have sex with men2
  • Injection drug-users2
  • People in healthcare facilities and correctional facilities2
  • Healthcare workers2
  • Most people from low-resource countries will contract hepatitis A in childhood1,2
  • Asians and Pacific Islanders are at higher risk of hepatitis B2

Because the different types of hepatitis cause similar symptoms during the acute phase, serological tests are important to determine the type of virus and when it was contracted. Once the serology results have been obtained (and possibly a liver biopsy performed to evaluate severity),appropriate treatment and management measures can be implemented.

Viral Hepatitis: Quick Guide to Serologic Markers

Situation

Hepatitis

Serologic markers

Acute hepatitis A
B C
D
E

Anti-HAV IgM
HBsAg / Anti-HBc IgM /Anti-HBc Total /HBeAg/Anti-HBe
Anti-HCV*
HDV IgM, Ag Delta
HEV IgM / HEV IgG

Chronic hepatitis B
C

HBsAg / Anti-HBc, then HBe Ag / Anti-HBe
Anti-HCV

Prenatal HBV screening B

HBsAg: if HBsAg + :

• Mother: monitored for HBe Ag / Anti-HBe and

• Newborn: quantitative anti-HBs after vaccination

At-risk groups B
C

Anti-HBc
• if – → vaccinate
• if + → quantitative HBsAg / Anti-HBs
Anti-HCV*

HBV vaccination B

Pre-vaccination: Quantitative Anti-HBs Total

• if – → vaccinate

• if + → quantitative HBsAg / Anti-HBc Total Post-vaccination: quantitative anti-HBs Total

HAV vaccination A

Patient > 30 years: Total anti-HAV

• if – → vaccinate

Prevention / Treatment

Prevention

The incidence of viral hepatitis is not distributed equally around the world. This is mainly due to lack of access to prevention measures in low-resource populations and countries. For this reason, the WHO global policy for the prevention and control of viral hepatitis aims to tailor responses to the specific national or regional context3. In general, this falls into alignment with essential global health strategies. For hepatitis, the most important prevention strategies are universal access to childhood vaccination for hepatitis B; improved hygiene and practices in and out of the healthcare setting; and screening.

Vaccination: Effective vaccines are available for hepatitis A and B2,3. The vaccine for HBV also protects against HDV, since HDV only affects populations already infected with HBV.

  • Universal vaccination in childhood is showing very good results in containing the number ofHBV infections.
  • Vaccination is helping to reduce mother-to-child transmissions (principal transmission for HBV)
  • Awareness and vaccination programs are also part of reducing the spread among adults, in particular at-risk groups. Vaccination is compulsory for some at-risk groups in some countries

Hygiene: Proper hygiene is an important prevention method for all types of viral hepatitis. This includes:

  • Clean drinking water and hygienic food handling
  • Proper hand washing
  • Safer sex
  • Injection drug users: not sharing needles and needle exchange programs
  • Health-care settings: fundamental infection control measures; aseptic techniques; no reuse of needles and syringes; safe injection practices

Screening: Screening of people in at-risk populations and of blood products is helping to reduce the spread of hepatitis2,3.

Treatment

Treatment for the various types of hepatitis varies greatly, as does treatment of acute versus chronic illness.

Hepatitis A
Usually resolves on its own. Treatment of symptoms includes rest and elimination of alcohol.

Hepatitis B
Acute HBV infection is not usually treated in immunocompetent adults, as it should resolve naturally.

Current treatments for chronic HBV5:

  • Pegylated Interferon alpha (Peg-IFN)
  • Nucleotides analogues (NAs):
    • First line: Entecavir (ETV), Tenofovir( TDF)
    • Second line: Adefovir, Telbivudine, Lamivudine
  • Liver transplant can be considered for decompensated cirrhosis
  • Therapeutic monitoring recommended during, at the end of treatment, and at a period after end of treatment

Hepatitis C
No specific treatment for acute HCV.

Reference treatment for chronic HCV6:

  • Genotype 1 (60% patients) Pegylated-interferon-α + ribavirin + Direct Antiviral Agent (Boceprévir or Telaprévir)
  • Other genotypes: Peg IFN + ribavirin
  • Treatment duration: 48 weeks for genotype 1, 24 weeks for other genotypes
  • Intermediate criterion to determine therapeutic efficacy: sustained viral response
  • Duration and efficacy of therapy depends on the genotype
  • Treatment monitoring should be done:
    • At T0 before starting therapy,
    • Regularly after several weeks of therapy, generally at weeks 4, 12, 24, 36, 48, etc.
    • Depending on genotype, drugs, viral response
  • New triple therapy treatments to become available in 20147:
    • PegIFN + RBV+ Sofosbuvir or Simeprevir
  • PegIFN-free regimens will also be available in 20147:

Hepatitis D
No specific treatment for acute HDV. See prevention and treatment of its helper virus, HBV.

Hepatitis E
Generally, no specific treatment for acute HEV, although treatment with Ribavirin may be effective. For immunocompromised patient, immunosuppressive treatment may be lowered. Otherwise, treatment is usually focused on relieving signs and symptoms.

Guidelines

  • WHO Guidelines on hepatitis B and C testing. 2017.
  • WHO: Global policy report on the prevention and control of viral hepatitis in WHO member states. 2013.
  • WHO: Guidance on prevention of viral hepatitis B and C among people who inject drugs. 2012.
  • CDC: Recommendations for Routine Testing and Vaccination for Chronic Hepatitis B virus Infection. 2008.
  • CDC: Recommended Testing Sequence for Identifying Current Hepatitis C Virus (HCV) Infection. 2013
  • American Association for the Study of Liver Disease/Infectious Diseases Society of America. Recommendations for Testing, Managing, and Treating Hepatitis. 14.02.2014
  • World Gastroenterology Organisation Practice Guideline for Hepatitis B. 2015.
  • EASL 2017 Clinical Practice Guidelines on the management of hepatitis B virus infection
  • European Association for the Study of the Liver. EASL Clinical Practice Guidelines: Management of hepatitis C virus infection. 2013.
  • Health Protection Agency (UK). Guidance for the Prevention and Control of Hepatitis A Infection. 2009.

1) WHO fact sheets: Hepatitis A (No 328), B (No204), and C (No 164), July 2013

2) CDC website: http://www.cdc.gov/hepatitis/

3) WHO: Global policy report on the prevention and control of viral hepatitis in WHO member states. July 2013.

4) Lefrère JJ, Lunel F, Marcellin P, Pawlotsky JM, Zarski JP. Guide pratique des hépatites virales. MMI Ed, Paris, 1998.

5) European Association for the Study of the Liver. EASL Clinical Practice Guidelines: Management of chronic hepatitis B virus infection. 2012.

6) European Association for the Study of the Liver. EASL Clinical Practice Guidelines: Management of hepatitis C virus infection. 2013 revision.

7) American Association for the Study of Liver Disease/Infectious Diseases Society of America. Recommendations for Testing, Managing, and Treating Hepatitis. 14.02.2014

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Diagnosing Hepatitis A, B & C

Transient Elastography

Doctors at NYU Langone are among the first in New York City to use transient elastography, an advanced imaging test, to measure how hard or soft the tissue of the liver is.

Stiffness in the liver suggests the presence of fibrosis, or scar tissue, generated in response to injury. The extent of stiffness indicates the extent of liver disease caused by viral hepatitis.

Transient elastography is very similar to ultrasound. Using a device called the FibroScan®, your doctor places a handheld probe against your abdomen, and the probe sends a painless vibration through the body and into the liver. A transducer on the end of the probe measures how long it takes for the vibration to travel through the liver. The faster the vibration passes through, the stiffer the liver is.

This quick and accurate test can take place in a doctor’s office, and often eliminates the need for a liver biopsy.

MRI and CT Scans

If the results of blood tests or ultrasound indicate you may be at risk for liver cancer, or if you have a family history of liver cancer and therefore are at increased risk, your doctor may recommend a CT scan or MRI scan to examine the liver in more detail. These imaging tests use computers to create two- or three-dimensional images of structures inside of the body.

Rarely, the results of imaging studies are not detailed enough to show the extent of liver damage, and a doctor may recommend a liver biopsy. A biopsy can determine the extent of scarring, or fibrosis, in a liver affected by viral hepatitis. Information provided by a biopsy can be used to guide treatment.

The doctor injects a local anesthetic into the skin to numb it, and then inserts a needle through the skin and into the liver, removing a tiny sample of liver tissue. Often, doctors use imaging, such as ultrasound or CT scanning, to guide the position of the needle. This tissue sample is sent to a laboratory for testing, and results are usually available in one week.

Hepatitis Testing

Your liver is the largest organ inside your body. It helps your body digest food, store energy, and remove poisons. Hepatitis is an inflammation of the liver. There are different types of hepatitis. Some are caused by viruses. They include hepatitis A, hepatitis B, and hepatitis C. To diagnose hepatitis, your health care provider will ask you about your medical history and symptoms, do a physical exam, and order blood tests.

There are blood tests for each type of viral hepatitis. Some tests check for antibodies to the virus. Antibodies are blood proteins that your immune system makes in response to the virus. Other blood tests look for parts of the virus, such as proteins or genetic material. Some tests show that you have the infection now. Other tests show that you have had it at some time, or that you have immunity to it.

Doctors use the tests to diagnose hepatitis, and to screen people who are at risk for hepatitis B or C. The risk factors are different for each type. Doctors may also use the tests in people who have hepatitis, to check how contagious they are or to see how well treatment is working.

Viral Hepatitis and Liver Disease

Laboratory Tests – Hepatitis C

Topic Review

National Hepatitis C Program Office
Drs. Rena Fox and Michael Surdy

Introduction

Laboratory tests for hepatitis C are divided into four general categories:

  • Screening: Screening for hepatitis C virus (HCV) is done with a serologic test for the HCV antibody (Ab).
  • Confirmatory: Diagnosis of chronic hepatitis C requires the presence of HCV RNA, commonly called hepatitis C viral load.
  • Genotype: Once it is determined that HCV RNA is present, the specific genotype and subtype of the virus can be determined with a genotype test.
  • Drug resistance: Mutations of some proteins in HCV can allow the virus to have resistance to direct-acting antivirals (DAAs), commonly referred to as resistance-associated variants (RAVs) or resistance-associated polymorphisms (RAPs).

HCV Serologic Testing (HCV Ab)

Enzyme immunoassays for Detection of Hepatitis C Antibody

The HCV Ab test is used for initial screening for hepatitis C. The test is performed by enzyme immunoassays (EIAs), which detect the presence of hepatitis C antibodies in serum. The result of the test is reported as positive or negative. Third-generation EIAs have a sensitivity/specificity of approximately 99%. However, the presence of HCV Ab does not indicate whether the infection is acute, chronic, or resolved. A positive antibody test result should be followed up with an HCV RNA test to confirm that viremia is present.

False-Negative and False-Positive HCV Ab Results

Despite the extremely high sensitivity and specificity of the EIA test for the antibody, it is still possible to have both false-positive and false-negative results.

False-Negative HCV Ab

  1. A false-negative HCV Ab result may occur if the test is performed during the window period after acute HCV infection but before seroconversion (when the HCV Ab converts from negative to positive). The average time from infection until seroconversion is 8 weeks and is referred to as the “serologic window.” If acute infection is suspected to have taken place within the past 8 weeks, it would be appropriate to order the HCV RNA test. If the HCV Ab test result is negative within the first 8 weeks after infection, it would be appropriate to retest the antibody after 8 weeks to check for seroconversion.
  2. A false-negative HCV Ab result may also occur in immunocompromised individuals such as those infected with HIV, recipients of organ transplants, and patients receiving chronic hemodialysis. If the HCV Ab result is negative in immunocompromised patients, but there is strong suspicion of HCV infection, it would be appropriate to order the HCV RNA test.

False-Positive HCV Ab

  1. A false-positive HCV Ab result may occur because of cross-reactivity with other viral antigens or the presence of immunologic disorders, such as lupus or rheumatoid arthritis.

Time for Processing HCV Ab Test Results

The turnaround time for 3rd-generation EIAs is at least 1 day. Many labs do not perform the tests on site and must send specimens to another lab for processing, which may further increase the turnaround time.

A point-of-care test is also available. The OraQuick® HCV Rapid Antibody Test is an FDA-approved test that can be performed with a fingerstick (or venous blood draw). It is also a CLIA-waived test and therefore can be used in clinic offices and outreach facilities. Results are reported as reactive or nonreactive within 20 minutes. Just as for the standard HCV Ab test done in the lab, a positive OraQuick® test must be confirmed by an HCV RNA test. The sensitivity and specificity of the test is similar to that of the laboratory-based assays.

Recombinant Immunoblot Assay for Confirmation of HCV Ab

Recombinant immunoblot assay (RIBA) is a highly specific test that in the past was used as a confirmatory test of antibody results. It still required HCV RNA testing for the diagnosis of chronic infection. The RIBA test is no longer in use or available in the United States.

HCV RNA Testing

The presence of HCV RNA is required to confirm chronic HCV infection. Therefore, a positive HCV Ab screening result must be followed by a test for the HCV RNA. The HCV RNA tests can detect virus within 1-2 weeks following exposure.

Appropriate Uses of the HCV RNA Test

There are 4 major reasons that HCV RNA tests are used:

  1. To confirm a positive HCV Ab result and make the diagnosis of current HCV infection
  2. To measure a patient’s baseline viral load prior to starting HCV therapy
  3. To monitor a patient’s response to therapy
  4. To determine whether a patient has achieved a sustained virologic response (SVR)

More rarely, HCV RNA is used when either very acute HCV infection is suspected or a false HCV Ab is suspected.

It would not be appropriate to repeatedly order HCV RNA viral load screening for a patient who is not on or was recently on HCV treatment, or to use the HCV viral load to determine the severity of the patient’s infection or the patient’s risk of developing significant liver disease.

HCV Antibody and HCV RNA Test Result Interpretations

Test Outcome Interpretation Further Action

HCV Ab nonreactive = negative

HCV Ab reactive = positive

HCV Ab negative Never exposed to HCV.
  • If the antibody result is negative (nonreactive), no further action is required.
  • If acute HCV is suspected, test for HCV RNA, as the HCV Ab result may not be positive yet.
HCV Ab positive Indicates exposure to HCV. Test for HCV RNA to determine chronic or resolved infection.
  • HCV Ab is positive in either active HCV infection or past HCV infection that has resolved. It is also possible to have a false-positive antibody result. The next step is to test for HCV RNA to determine if there is active infection.
  • Once the HCV Ab result is positive, the test does not need to be repeated in the future. The result will remain positive.
  • The antibody result also will remain positive after successful HCV treatment (achievement of an SVR).
HCV Ab positive, HCV RNA detected Active HCV infection. If infection occurred >6 months ago, this is chronic HCV infection.
  • Provide the patient who was tested with appropriate counseling and link that person to medical care, including treatment.
HCV Ab positive, HCV RNA not detected No active HCV infection. Patient spontaneously cleared HCV and did not become chronically infected, or was successfully treated and achieved SVR.
  • No further action required in most cases
  • If there is concern about a false-positive antibody screen, consider a repeat HCV Ab test using a different assay.

HCV Reflex Testing

Per VA policy, an HCV RNA test is automatically performed on all positive HCV antibody specimens (reflex testing). The reflex process helps in the clinical management of the patient by avoiding the need for a patient to return for a second blood draw if the antibody result is positive.

Meaning of HCV Viral Load

The number of HCV RNA international units per milliliter of blood (i.e., the viral load) must be measured before treatment and during the course of treatment, to assess response. Before treatment, however, the HCV viral load is not related to the patient’s liver disease severity or HCV prognosis. This is important for patients and providers to understand.

Note: In hepatitis B, unlike hepatitis C, a higher HBV DNA viral load does correlate with increased disease severity and increased likelihood of outcomes such as hepatocellular carcinoma.

Specific HCV RNA Assays and Range of Detectable Virus

HCV RNA tests use target amplification techniques. Several assays exist for HCV RNA testing. Methods include polymerase chain reaction (PCR), transcription mediated amplification (TMA), and branched chain DNA (bDNA) tests. Results are expressed as international units/mL (IU/mL). The different methods and different commercial assays each have a lower limit of quantification (LLOQ) and lower limit of detection (LLOD), therefore a patient’s results could be reported differently depending on the assay used. HCV RNA tests must have an LLOQ of 25 IU/mL or lower when used to assess treatment response with DAAs.

LLOQ = the lowest HCV RNA level that is within the linear and analytically acceptable range of the assay.

LLOD = the lowest level of HCV RNA that is detected ≥95% of the time.

Interpreting HCV RNA Test Results

It is essential that the provider understands how to interpret HCV RNA test results, especially during the course of HCV treatment.

Result of HCV RNA Test Interpretation
A quantified viral load — any exact number Ongoing HCV infection
“Detected” The HCV RNA is detectable but the number of international units is so low that it cannot be quantified accurately. This indicates extremely low level of virus is present.
“<12 IU/mL” or “<15 IU/mL” or “<25 IU/mL” All of these are “less than the LLOQ” HCV RNA is undetectable. No virus is detected at all in the patient’s serum specimen.

HCV Genotype Testing

There are at least six HCV genotypes. These are classified as genotypes 1-6. There are also 30 subtypes of HCV, which are referred to as genotypes 1a, 1b, 2a, etc. Identifying HCV genotypes is essential for selecting treatment regimens and predicting treatment response. Within genotype 1, it is also important to determine whether the patient is subtype 1a or 1b, as this determines treatment duration and the need for ribavirin in the treatment regimen. Patients only need to be genotype tested once in their lifetime, as the genotype remains the same throughout the course of infection. Repeating a genotype test is warranted only if there is suspicion that a patient may have been reinfected with a different genotype after achieving an SVR.

Genotype testing is performed by analyzing the sequences of various regions of the HCV genome. Most genotype assays rely on the amplification of short HCV RNA regions from clinical specimens, followed by a type-specific assay, such as restriction fragment length polymorphism (RFLP) analysis, line probe reverse hybridization, or sequence analysis. Most assays target the 5′ untranslated region (5′ UTR), as it is the most conserved region throughout the HCV genome and is most suitable for reverse transcription polymerase chain reaction (RT-PCR) amplification.

HCV Resistance Testing (RAV testing)

DAAs are drugs that target specific steps in the life cycle of the hepatitis C virus. When these steps are disrupted, replication of HCV is stopped. DAA drug classes include NS5A inhibitors, NS5B polymerase inhibitors, and NS3/4A protease inhibitors. Resistance Associated Variants (RAVs) refer to mutations that occur in the target enzymes that confer resistance to DAAs. RAV testing is done in most patients who have failed a prior DAA-containing regimen before they initiate re-treatment with another DAA regimen. For example, genotype 3 patients are recommended to have RAV testing if they are treatment experienced before starting re-treatment with sofosbuvir/velpatasvir and to determine whether ribavirin is needed. RAV testing is occasionally done in treatment-naive patients if it may change the regimen or the duration of treatment. For example, genotype 1a patients who are treatment naive should be RAV tested before starting treatment with elbasvir/grazoprevir to determine whether ribavirin is needed or whether an extended duration of treatment is needed. Genotyping of the NS5A, NS5B, and NS3/4A genes to identify RAVs can now be accomplished by RT-PCR and population-based sequencing methods at the VA Palo Alto Public Health Reference Laboratory (PHRL) and at commercial laboratories including Monogram Biosciences (LabCorp) and Quest Diagnostics. HCV drug resistance testing should be ordered only by experienced HCV clinicians.

  1. Centers for Disease Control and Prevention. Testing for HCV infection: an update of guidance for clinicians and laboratorians. MMWR Morb Mortal Wkly Rep. 2013 May 10;62(18):362-5.
  2. Carrazin C. The importance of resistance to direct acting antiviral drugs in HCV infection in clinical practice. J Hepatol. 2016 Feb;64(2):486-504.

Hepatitis

Sources Used in Current Review

Centers for Disease Control and Prevention (27 August 2015 updated). Hepatitis A FAQs for the Health Professionals. Available online at http://www.cdc.gov/hepatitis/hav/havfaq.htm#general. Accessed April 24, 2016.

Centers for Disease Control and Prevention (16 December 2015 updated). Hepatitis B FAQs for the Health Professionals. Available online at http://www.cdc.gov/hepatitis/hbv/hbvfaq.htm. Accessed April 24, 2016.

Centers for Disease Control and Prevention (31 May 2015 updated). Hepatitis A FAQs for the Health Professionals. Available online at http://www.cdc.gov/hepatitis/hcv/index.htm. Accessed April 25, 2016.

Centers for Disease Control and Prevention (8 December 2015 updated). Hepatitis D FAQs for the Health Professionals. Available online at http://www.cdc.gov/hepatitis/hdv/index.htm. Accessed April 25, 2016.

Centers for Disease Control and Prevention (28 August 2015 updated). Hepatitis E FAQs for the Health Professionals. Available online at http://www.cdc.gov/hepatitis/hev/index.htm. Accessed April 25, 2016.

National Institute of Diabetes and Digestive and Kidney Diseases. LiverTox. Available online at http://livertox.nih.gov/intro.html. Accessed April 25, 2016.

University of Maryland School of Medicine Institute of Human Virology. Drug-induced Hepatitis Information Guide. Available online at http://www.ihv.org/education/drug_hep.html. Accessed April 26, 2016.

NIDDK. Autoimmune Hepatitis. Available online at http://livertox.nih.gov/Phenotypes_auto.html.

Sources Used in Previous Reviews

National Institute on Alcohol Abuse and Alcoholism. Alcohol and the Liver. No. 19 PH 329 January 1993. Available online at http://pubs.niaaa.nih.gov/publications/aa19.htm. Accessed November 2009.

(August 22, 2008) Younossi Z. Review Article: Current Management of Non-Alcoholic Fatty Liver Disease and Non-Alcoholic Steatohepatitis. Medscape Today. Available online at http://www.medscape.com/viewarticle/578709. Accessed October 2009.

National Digestive Disease Information Clearinghouse. Autoimmune hepatitis. Available online at http://digestive.niddk.nih.gov/ddiseases/pubs/autoimmunehep/. Accessed October 2009.

University of Wisconsin, School of Medicine and Public Health. Health Information: Autoimmune liver disease panel. Available online at http://apps.uwhealth.org/health/hie/1/003328.htm. Accessed October 2009.

Fischbach, F.T., (2004) A Manual of Laboratory & Diagnostic Tests. 7th Edition., Lippincott Williams & Wilkins, Philadelphia.

Henry’s Clinical Diagnosis and Management by Laboratory Methods. 22nd ed. McPherson R, Pincus M, eds. Philadelphia, PA: Saunders Elsevier: 2011, Pp 308-309.

(February 16, 2012) National Digestive Diseases Information Clearinghouse. Autoimmune Hepatitis. Available online at http://digestive.niddk.nih.gov/ddiseases/pubs/autoimmunehep/. Accessed October 2013.

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