How Hepatitis C Virus Is Diagnosed

hepatitis C diagnosis
© Verywell, 2018

Hepatitis C virus (HCV) is usually diagnosed with blood tests. An antibody test can detect whether your body has had to fight off HCV infection. A blood test which measures the virus in your blood confirms the diagnosis, but results take longer.  Sometimes, liver function tests, imaging studies, or a biopsy can support or confirm the diagnosis as well. 

Self-Checks/At-Home Testing

If you think that you may have HCV, there are a few signs you can try to look for on your own. The problem, however, with self-checks for HCV, is that many of the signs you can observe are common to most viral infections. Some of the signs you can look for are signs of liver disease, but they are not specific to HCV. 

Skin and Eyes

The sign that is most characteristic of HCV is jaundice, a yellowish color of the skin and eyes. Jaundice affects the whole body and the white part of the eyes. This color can appear as mildly yellow, almost like a suntan, or, if the infection has had a major impact on liver function, your eyes and skin might become an extremely deep yellow color. 

Jaundice indicates liver failure or liver dysfunction, so it is not specific to HCV. 

Abdominal Distension

Expansion of the abdominal area, with or without discomfort, is common in late-stage HCV. Many people do not have any signs of HCV in the early stages of infection, and abdominal distention can be the first clue that you have HCV. 

Flu-Like Symptoms

If you have active HCV infection, you might have a mild fever, fatigue, muscle aches, loss of appetite, nausea, and stomach discomfort. You can experience this with almost any viral infection, so it is not a strong clue that you have hepatitis. 

Gastrointestinal Symptoms

If you have an active HCV infection, you are likely to experience stomach upset, nausea, vomiting, or diarrhea. As with the flu-like symptoms, this is not a definite sign of HCV infection, as it can occur with other infections as well. 

Risk Factors

Most of the time, you will not know right away if you have been infected with HCV. Carefully thinking about whether you have any risk factors is the best way to check if you might have HCV. 

If you have risk factors or any of the signs of HCV, it is recommended that you get tested for the virus. 

Labs and Tests

There are several blood tests that can diagnose HCV infection, determine the best course of treatment, and monitor your progress. Blood tests can check for HCV antibody, for HCV itself, and for liver function changes. 

HCV Antibody Blood Tests

When hepatitis C viruses infect your liver cells, your immune system responds by using antibodies to mark the viruses as harmful intruders. The antibodies are specific for HCV, so their presence indicates that you have had HCV at some time in your life. Antibody tests cannot distinguish between past or current infection, so clinical information such as medical history, signs, symptoms, or other tests can determine whether you have an active infection or a previous infection. In fact, a positive antibody test may mean that you have had an infection that you successfully fought off, and that you are essentially immune to HCV. 

  • Blood Test: Enzyme-Linked ImmunoSorbent Assay (ELISA) tests can detect antibodies in your blood. There are many different ELISA tests. The ELISA test for HCV searches the blood sample for the HCV antibody. If antibodies are found, this means that you might have HCV infection. The ELISA test is very sensitive and is positive 95 percent of the time if you have HCV antibodies. This high sensitivity means that when the ELISA test is negative, you can feel very confident that you do not have HCV. However, it is so sensitive that it may incorrectly identify HCV antibodies, and there is a small possibility that a positive result could be incorrect. Because of the chance of a false positive result, a second test may be needed to verify the original results. 
  • Rapid Test: The rapid test can detect HCV in your blood or saliva with 89 percent sensitivity and 100 percent specificity. This means that it is not as sensitive as the ELISA test and can miss the presence of HCV sometimes. But if the test is positive, then you can be certain that you have or have had HCV in your body at some time.  

    Hepatitis C RNA

    The detection of HCV RNA, which is genetic material of the virus, indicates that the virus itself is present in your body. This powerful test also allows doctors to see how well you are responding to treatment because it can determine the amount of virus in your blood, which is often called the viral load. It detects the virus by using PCR technology (polymerase chain reaction), which is a method of detecting genetic material. 

    Using ELISA and HCV RNA tests together:

    • Negative ELISA = No hepatitis C antibodies found in blood. You are probably not infected with HCV.
    • Positive ELISA = You may have HCV infection. However, it is possible this is a false-positive. More testing is required.
    • Negative HCV RNA = No active HCV infection.
    • Positive HCV RNA = Active HCV infection.

    Hepatitis C Virus Genotyping

    Hepatitis C viruses are not all the same. Certainly, they are all identified as hepatitis C viruses and they all can cause acute and chronic hepatitis C infection, but they are not exactly genetically alike. They have slightly different genetic variations and are grouped into different genotypes (genetic types). Knowing your genotype can significantly reduce the duration of your treatment because your doctor can select the right treatment for the type of HCV you have.

    Genotypes are important because hepatitis C viruses with different genetic variations require different treatment approaches. Doctors determine your HCV genotype with a laboratory test that uses a method called reverse transcription polymerase chain reaction (RT-PCR). This test analyzes the genetic material of the virus to determine its sequence, which identifies the virus's genotype. 

    Liver Function Tests (LFTs)

    Liver function tests can be abnormal if the virus and the inflammation cause damage to the liver. These tests generally are not expected to be abnormal until late stages. And treatments for HCV can also change LFT levels.

    The LFTs that become altered if you have liver dysfunction include:

    • Albumin
    • Bilirubin
    • Prothrombin Time (PT)
    • International Normalized Ratio (INR)

    LFTs that can become altered if you have inflammation of the liver include:

    • Alanine aminotransaminase (ALT)
    • Aspartate aminotransferase (AST)
    • Gamma-glutamyl transaminase (GGT)

    Imaging

    Imaging tests can identify inflammation of the liver, enlargement of the liver, shrinking of the liver, or tumors in the liver. Imaging results cannot specifically identify HCV infection. Any of these consequences can occur as a result of HCV infection, although they can occur with any liver disease as well. You might need to have imaging tests if you have abdominal distention, severe jaundice, or symptoms that suggest that you might have cancer. You also may need imaging tests if your doctor is concerned about other possible diagnoses that can be identified on abdominal imaging tests, such as appendicitis or gallstones. 

    • Abdominal Ultrasound: This test can evaluate abnormalities in the liver and abdomen, and may also detect the fluid build-up in the abdomen, which can occur with liver failure. 
    • Computerized Axial Tomography (CT) scans: An abdominal CT scan can detect changes in the size and density of the liver and may visualize masses or signs of early cancer. 
    • Magnetic Resonance Imaging (MRI): An MRI can pick up on abnormalities that suggest liver dysfunction or cancer. 
    • Liver Biopsy: A liver biopsy is a section of tissue taken from the liver and evaluated under a microscope to look for identifying features of the disease. The procedure is often guided by abnormal lesions noted on imaging studies. 

    Differential Diagnoses

    Several different medical problems can cause abnormal LFTs and produce symptoms similar to those of HCV infection. However, none of these conditions can cause you to have a positive HCV antibody blood test or a positive HCV RNA test. 

    • Alcoholic Hepatitis: Alcoholism can cause several serious problems in the liver, including fatty liver, cirrhosis, and cancer. The development of alcoholic liver disease occurs gradually over time, and imaging studies may show different patterns than what would be expected with HCV.  
    • Hepatitis B (HBV): The pattern of illness with HBV is more severe than that of HCV, although there can be similarities because they are both viruses that affect the liver.
    • Hepatitis A (HAV, hep A): Another virus that causes hepatitis, like HCV, hep A, can cause flu-like symptoms. This virus is transmitted through contaminated food. It spreads because the virus is present in the stool (poop) and can be spread from person to person due to improper handwashing. 
    • Cholecystitis (inflammation of the gallbladder) or Choledocholithiasis (gallstones): Gallstones or inflammation of the gallbladder can cause jaundice, nausea, vomiting, and fever. Cholecystitis and choledocholithiasis may be painful as well. 
    • Appendicitis: Inflammation or infection of the appendix cause severe abdominal pain and fevers, and develops quickly. Sometimes, appendicitis can be mistaken for HCV infection if the pain of appendicitis is mild. HCV infection can be mistaken for appendicitis if the pain and abdominal discomfort are worse than the usual HCV symptoms. 
    • Hepatocellular Carcinoma: Cancer of the liver can cause abdominal distension, jaundice, and abnormal LFTs. Cancer of the liver may also develop as a result of late-stage HCV. It is important to determine if HCV was the cause of the cancer because the virus and cancer would both need to be treated. 
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