Testing for hepatitis C is usually straightforward as the blood tests are fairly sensitive and specific. However, there is a set protocol to follow for these tests to provide enough value.
A person's hepatitis C status can only be determined conclusively if they have had both an antibody test and an HCV RNA test following the window period of hepatitis C. Tests carried out during the window period are more likely to give false-negative results. Similarly, a single, positive anti-HCV antibody test is not conclusive for diagnosing hepatitis C. An HCV RNA test is usually needed to conclude if a person has an ongoing viral infection caused by HCV.
While it sounds complicated, the protocol for hepatitis C testing is straightforward and effective. Learning about each component of this protocol allows you to understand the testing procedure more easily.
WHEN IS A HEPATITIS C TEST CONCLUSIVE?
A hepatitis c test is only accurate if it is taken during a certain period. When taken before or after this period, the testing kit cannot accurately determine the presence of the hepatitis C virus in the body. This results in low sensitivity and specificity of the test and renders it useless to detect hepatitis C.
The testing kit for hepatitis C has a specific window in because of the very nature of the test. The most commonly used test for the detection of hepatitis C is the anti-HCV antibody test. This test detects the presence of anti-HCV antibodies in the blood, which are formed in response to the hepatitis C virus entering the body.
Since the test is reliant on the development of the antibodies, the test cannot yield accurate results until the antibodies have been given a fair chance to form. During the window period, which is the time period between infection and seroconversion, there are no antibodies to detect. Once seroconversion, or the development of antibodies, occurs, the testing kit can get the job done efficiently.
The window period for the development of anti-HCV antibodies s 4-10 weeks. Generally, it can take up to 6 months for these antibodies to develop. Rarely the window period can prolong, and it can take up to 9 months before any antibodies can be detected in the blood.
Since testing will mostly return a "false-negative" result during the window period, it only makes sense to conduct the antibody test after six months. The latest CDC protocol for hepatitis C testing advises an initial anti-HCV antibody testing when the patient presents with symptoms and another antibody test 6 months after.
WHAT IS AN HCV RNA TEST?
Although the anti-HCV antibody test is the initial test of choice for diagnosing hepatitis C, the HCV RNA test is also frequently employed to provide an accurate diagnosis.
The HCV RNA test is different from the antibody detection test as it detects a much more direct parameter of viral presence in the blood: the viral RNA. The hepatitis C virus is an RNA virus, and the detection of this viral RNA provides a clear picture of whether a person is infected with hepatitis C or not.
The HCV RNA testing kit detects viral RNA and quantifies it, essentially giving a critical value known as the viral load. The viral load is a direct indicator of their health following a viral infection. Greater viral loads indicate a severe infection with a poor prognosis, while lower to insignificant viral loads indicate a mild infection or an improving infection.
Moreover, the HCV RNA test can also detect the presence of the hepatitis C virus earlier than the antibody test. The HCV RNA test usually returns an accurate result 2-3 weeks after infection with HCV.
While the HCV RNA test is more specific and more sensitive, it is not used alone to diagnose hepatitis C. Both the antibody test and the RNA test are used in conjunction to provide an accurate diagnosis. After an initial positive antibody test, the viral RNA test is employed to differentiate between an active hepatitis C infection and a previous hepatitis C infection that may or may not have resolved.
SHOULD I GET TESTED FOR HEPATITIS C?
The most common indication for getting tested for hepatitis C is developing the signs and symptoms of this disease. Common symptoms of hepatitis C include:
- Abdominal pain
- Yellowing of the skin and the eyes
- Dark-colored urine
These symptoms can appear in a person infected with the hepatitis C virus. Consider visiting your physician at the earliest if you develop any or all of these symptoms.
Another indication for getting tested for hepatitis C is for screening purposes. Screening aims to diagnose a condition before any signs or symptoms appear. The CDC recommends that adults over 18 years and pregnant women undergo hepatitis C screening at least once in their lives.
I TESTED POSITIVE FOR HEPATITIS C, BUT I HAVE NO SYMPTOMS
It is possible to have hepatitis C without showing any signs or symptoms for the longest time. This is because hepatitis C does not always cause any symptoms to appear, and when it does, the symptoms are very non-specific. However, it is also a possibility that your blood test was simply a false-positive test, in which case the test would have to be repeated.
While getting a false-positive test result can be troublesome, it rarely poses a problem since all medical facilities conduct a two-stage testing algorithm to detect hepatitis C. a single positive blood test for hepatitis C always needs to be supplemented with another positive test result.
When you get a positive blood test for hepatitis C, your doctor will ask you to return with a repeat test 3 months later. If your first positive test were an anti-HCV antibody test, your doctor would also ask you to complete a PCR test. The PCR test for hepatitis C is also known as the viral RNA test.
This HCV RNA test checks for the viral RNA in a person’s blood and confirms the diagnosis of a current, ongoing infection if viral RNA is found in the blood.