Understanding viral load and hepatitis B infections

Young asian doctor discussing test result and diagnosis with senior couple patients using digital tablet in hospital hallway

Hepatitis B, sometimes abbreviated to HBV, is a liver infection that is one of the most serious in the world. If left untreated, hepatitis B can cause fibrosis, cirrhosis, hepatocellular carcinoma, and end-stage liver disease.

When a person is suspected to have hepatitis B, doctors will run a series of tests to determine what stage the infection has reached and if it is currently causing harm to the liver. One of these theses is the HBV DNA (viral load test), which can provide a plethora of information for both doctors and patients. 

What a hepatitis B viral load test can tell you about your infection

The hepatitis B virus DNA quantification, also known as the viral load test, is a blood test that measures the amount of hepatitis B virus DNA (viral load) in an infected person’s blood using a Polymerase Chain Reaction (PCR) technique. By itself, this hepatitis B test can provide insight into an individual's viral load, and when assessed in relation to other markers — such as a person’s e-antigen (HBeAg) status, liver enzymes (ALT/AST) test results, and inflammation levels — even more valuable information can be gained. 

What is viral load in relation to hepatitis B?

An individual’s viral load, usually measured in “international units per milliliter” (IU/mL), can vary over time and relates to the current phase of a hepatitis B infection. By having viral load monitored regularly, individuals can work with their doctors to understand more about the severity of their infection and to determine the best course of treatment.

The phases of hepatitis B

There are four phases that characterize a chronic hepatitis B infection. The length of the phases varies from person to person, and not everyone will experience all four. Additionally, the experience of these phases is not linear, and many people living with hepatitis B will transition between them throughout their infection period.

  • Immune-Tolerant Phase: In the immune-tolerant phase, the hepatitis B infection is able to reproduce freely in the body and replicate quickly, without causing damage to the liver. After a person’s immune system generates antibodies in response, the viral load will decline and ALT/AST levels will normalize. For healthy adults, this stage is often short-lived; though for people who have had hepatitis B since infancy, it can last for years or decades.
  • Immune-Active/Immune-Clearance Phase: This stage occurs when a person experiences elevated or fluctuating levels of ALT, HBV viral loads around 20,000 IU/mL or greater, and active liver inflammation. This typically occurs after a person is in the immune-tolerant phase. Individuals will eventually develop HBeAg-positive chronic hepatitis, which includes elevated ALT levels and active liver inflammation that can be accompanied by liver fibrosis. At some point, most individuals with HBeAg-positive chronic HBV will lose HBeAg and seroconvert spontaneously anti-HBe (antibody of HBeAg). 
  • Inactive Carrier State: Eventually, most people will transition into the inactive hepatitis B phase, which is characterized by undetectable or low viral loads (less than 2,000 IU/mL) and improvements in liver inflammation and fibrosis. In this phase, adults will typically have normal ALT levels and minimal inflammation, but it is important that doctors are on alert for evidence of advanced liver disease. This phase may be lifelong, decades, or not long at all. 
  • Reactivation Phase: People who are HbeAg negative may experience reactivation, which occurs when ALT loads are elevated, HBV viral loads are above 2,000 IU/mL, and liver inflammation and fibrosis levels are moderate-to-severe.

Regardless of the phase, it is important to regularly monitor HBV DNA levels. If a person is taking antiviral medications, measuring these levels can be a good indicator of whether or not a drug is working to actively reduce viral loads. 

Is hepatitis B curable?

Because hepatitis B is not a curable condition, it can feel isolating and scary to receive a diagnosis. However, there are hepatitis B support groups that many patients enjoy being a part of. Additionally, clinical trials are often testing the safety and efficacy of investigational treatments for hepatitis B. To learn how to find research studies near you, click the button below.