Viral load tests measure the amount of virus in the blood. Your viral load can indicate how well your body is responding to treatment, but can’t be used to measure the progression or severity of hepatitis C.

Hepatitis is a disease of the liver. There are several types of hepatitis, each named for the type of virus that causes it.

The hepatitis C virus (HCV) can be transferred through contact with the blood of someone with hepatitis C or during sexual contact. A birthing parent with hepatitis C can transmit the virus to their infant during childbirth.

Not everyone with hepatitis C has symptoms. In fact, in a small number of people, the infection resolves on its own. However, a hepatitis C infection can last anywhere from a few weeks to a lifetime.

The illness can lead to:

  • liver damage
  • liver cancer
  • the need for a liver transplant

Certain tests can be used to confirm an infection and evaluate treatment outcomes, including viral load tests, which measure the amount of virus in the bloodstream at any given time.

Viral load tests can confirm an active hepatitis C infection.

Once you start treatment, viral load testing can be used to monitor its success and guide future healthcare decisions.

Two types of tests are widely used for hepatitis C. These include the hepatitis C virus antibody test and hepatitis C virus RNA assays.

Hepatitis C virus antibody test

An HCV antibody test is a simple blood test used for screening purposes. While this test can detect that HCV has been in your bloodstream, it can’t tell the difference between a previous infection and an active one.

In some cases, a weak positive result can turn out to be a false positive.

If you test positive for HCV, a doctor will likely follow up with additional testing to measure your viral load and determine if you have an active infection.

Hepatitis C virus RNA assays

The HCV RNA qualitative test can tell the difference between past and current infections. This test measures the amount of virus in your blood, also known as the viral load.

A third test, viral genotyping, can zero in on the specific HCV in your body.

There are several different types of HCV. Knowing the specific form of HCV that you have is important, as it may factor into decisions regarding the most effective treatment for you.

With certain other infections, having a higher viral load can mean a higher level of illness, but that isn’t the case with hepatitis C. Your viral load has no bearing on how ill you feel or how much liver damage you may experience now or in the future.

However, viral load is an important indication of how well treatment is likely to work. The lower your viral load, the more likely your treatment is to be successful.

Here is how doctors define high, low, and undetectable viral loads:

Viral load
Lowless than 800,000 international units (IU) per milliliter (mL)
Highmore than 800,000 IU/mL
Undetectableless than 15 IU per liter (L)
Sustained virological responsenot detected at least 12 weeks after completing treatment

A doctor may use viral load tests to evaluate how your body is responding to medications used to treat hepatitis C. During treatment, a falling viral load is an indication that treatment is succeeding.

At the end of the planned course of treatment, which generally occurs around 8 to 12 weeks, an undetectable viral load means that you can finish treatment.

A sustained virologic response is when the most sensitive tests find no trace of HCV 12 weeks after stopping treatment. After that, viral load testing can alert you to a relapse.

Keep in mind that viral load tests do not indicate how quickly the condition is progressing or the severity of symptoms. Instead, doctors use viral load testing to guide medical decisions at each stage of treatment.

Understanding the specifics of your viral load is important at the time of diagnosis. Once you begin treatment, follow-up testing will let the doctor know if the current treatment is effective.

Other than that, there’s typically no need for repeat testing. This is because the viral load doesn’t provide information about your symptoms or whether your liver is functioning properly.

Other liver tests, such as a biopsy, can provide that information.

Certain groups are more vulnerable to contracting HCV and doctors may recommend testing for HCV. These groups can include:

  • people on dialysis
  • children born to HCV-positive mothers
  • anyone who may have had contact with the blood of someone with hepatitis C

The most common methods of HCV transmission are:

  • sharing needles and syringes used for injecting drugs
  • a mother with hepatitis C transferring HCV to her child during childbirth

Occasionally HCV is transmitted through:

  • having sex with someone who has hepatitis C
  • getting a tattoo in a place that doesn’t have proper infection control
  • sharing personal care items, such as a razor or toothbrush, with someone who has hepatitis C

Hepatitis C can’t be transmitted through:

  • coughing or sneezing
  • sharing silverware or glassware
  • hugging and kissing
  • breastfeeding
  • holding hands

There are often no symptoms of hepatitis C. However, some people may experience:

  • fatigue
  • abdominal pain
  • jaundice

Those symptoms may prompt a doctor to order an HCV test.

Antibodies don’t always show up in the first months after exposure.

If you’ve tested positive for HCV, it’s important that you get tested for viral load. Viral load testing is also advised prior to and during treatment.

The following includes frequently asked questions about hepatitis C viral load.

At what viral load do you treat hepatitis C?

Both high and low viral loads require treatment. A doctor may recommend discontinuing medications once the viral load is undetectable and the planned course of treatment is completed.

What is the range of hepatitis viral load?

A viral load of less than 800,000 IU/mL is considered low, while a viral load of over 800,000 IU/mL is considered high. A viral load below 15 IU/L is defined as undetectable.

Meanwhile, a sustained virological response is achieved once hepatitis C is not detected in the blood after at least 12 weeks of completing treatment.

What are the symptoms of a high viral load of hepatitis C?

Many people with a high viral load of hepatitis C may not experience any symptoms. But when symptoms occur, they can include fever, fatigue, stomach pain, loss of appetite, and jaundice.

Viral load testing can help determine the amount of hepatitis C in the blood to monitor how well your body is responding to treatment.

Though your viral load cannot help predict the progression or severity of hepatitis C, it can be used to evaluate how likely a treatment is to be successful.

For this reason, viral load testing is typically recommended both prior to and during treatment for hepatitis C.