Hepatitis B is a viral infection that affects the liver and can be both a short-term illness or a lifelong condition. Understanding when and how to get tested is crucial, as many people with the virus don’t experience symptoms but can still spread the infection and face serious health risks over time.

Introduction: Who Should Get Tested for Hepatitis B

Many people living with hepatitis B don’t know they’re infected because the virus often causes no symptoms at all. In fact, about 1 in 2 people with hepatitis B are unaware of their condition.^[1] This makes testing especially important, as the virus can be present in your body for years without you feeling sick, all while potentially causing liver damage.

You should consider getting tested for hepatitis B if you belong to certain groups at higher risk. If you were born in countries where hepatitis B is common—such as parts of Asia, Africa, South America, the Middle East, or the Caribbean—testing is advisable.^[3] The same applies if your parents were born in these regions, as the virus is often passed from mother to child during birth.

Testing is also recommended for people who inject drugs or share needles, those who live with or have sex with someone who has hepatitis B, and men who have sex with men.^[4] Healthcare workers who may be exposed to blood, people receiving dialysis, and those with certain chronic conditions like HIV, hepatitis C, or chronic liver disease should also seek testing.^[9]

All pregnant women need to be tested for hepatitis B at their first prenatal visit during each pregnancy.^[9] This is essential because if a mother has the virus, her baby can be infected during birth and is at very high risk of developing a chronic, lifelong infection. Babies infected at birth have about a 90% chance of the infection becoming chronic.^[6]

Even if you don’t fit into any high-risk category, you can still ask your doctor about testing. If you’ve been exposed to someone else’s blood or body fluids, if you’ve had unprotected sex with multiple partners, or if you’ve received tattoos or piercings with equipment that may not have been properly sterilized, testing can provide peace of mind and early detection if needed.

Diagnostic Methods for Hepatitis B

Diagnosing hepatitis B involves blood tests that look for specific markers of the virus. Your healthcare provider will perform a physical examination first, checking for signs of liver damage such as yellowing of the skin and eyes (called jaundice), stomach pain, or swelling in the abdomen.^[9] However, because symptoms are often absent, blood tests are the primary way to identify the infection.

The main blood test used to screen for hepatitis B looks for something called hepatitis B surface antigen, or HBsAg. This is a protein on the surface of the virus, and if it’s found in your blood, it means you currently have a hepatitis B infection.^[9] This test can’t tell you by itself whether your infection is acute (short-term) or chronic (long-term), but it’s the starting point for diagnosis.

If the HBsAg test comes back positive, your doctor will order additional blood tests to learn more about your infection. These tests measure other markers in your blood, such as antibody to hepatitis B surface antigen (anti-HBs), which indicates immunity, and antibody to hepatitis B core antigen (anti-HBc), which shows past or current infection.^[20] Together, these markers help determine whether your infection is new, ongoing, or whether you’ve recovered and are now immune.

Another important blood test measures the amount of virus in your blood, known as HBV DNA levels. This test tells your doctor how active the virus is and helps guide decisions about whether treatment is needed.^[9] Higher levels of HBV DNA often mean the virus is actively replicating and may be causing more liver damage.

Your healthcare provider may also check your liver function by measuring levels of certain enzymes in your blood, such as alanine aminotransferase, or ALT. Elevated ALT levels can indicate that your liver is inflamed or damaged.^[7] This helps doctors understand how much harm the virus is causing to your liver.

In some cases, additional tests are needed to assess the extent of liver damage. A special type of ultrasound called transient elastography, sometimes known by the brand name Fibroscan, can measure the stiffness of your liver, which indicates scarring or fibrosis.^[9] More severe scarring is called cirrhosis, and this test helps doctors see how far liver damage has progressed without needing surgery.

A liver biopsy may be performed in certain situations. During this procedure, a thin needle is inserted through your skin and into your liver to remove a small tissue sample.^[9] This sample is then examined in a laboratory to check for damage or scarring. Although a biopsy provides detailed information, it’s not always necessary, especially with the availability of non-invasive tests like elastography.

Regular liver ultrasounds are also used to screen for liver cancer, which is a serious complication of chronic hepatitis B. People with chronic infection, especially those with cirrhosis or a family history of liver cancer, should have ultrasounds every six months to catch any tumors early.^[9]

Diagnostics for Clinical Trial Qualification

When researchers conduct clinical trials to test new treatments for hepatitis B, they use specific tests to decide which patients are eligible to participate. These tests ensure that participants meet the criteria needed to evaluate whether a new drug or therapy is safe and effective.

Blood tests are central to qualifying patients for hepatitis B clinical trials. Researchers typically require confirmation that a person has chronic hepatitis B, which means the hepatitis B surface antigen (HBsAg) must be present in the blood for at least six months.^[7] This confirms the infection is long-term rather than a recent, acute case.

Trials often measure HBV DNA levels to determine how active the virus is in each participant’s body. Many studies set minimum or maximum HBV DNA thresholds for enrollment, as they need to test treatments in people with varying levels of viral activity. For example, some trials might focus on people with very high viral loads, while others might include those whose virus is less active.

Liver function tests are also standard for trial qualification. Researchers check ALT levels and other liver enzymes to assess how much inflammation or damage is present. Some trials specifically enroll people with elevated ALT levels because these individuals have active liver inflammation and are more likely to benefit from new treatments.^[14]

Assessing the stage of liver damage is another key part of determining eligibility. Clinical trials may use elastography or liver biopsies to measure fibrosis and cirrhosis. Some trials are designed for people with early-stage disease, while others focus on those with advanced liver scarring. Knowing the stage of liver damage helps researchers understand whether a treatment works better at certain points in the disease’s progression.

Additionally, trials may test for the presence of hepatitis B e antigen, or HBeAg, in the blood. This marker indicates higher levels of viral replication and infectiousness. Some treatments are specifically designed for people who are HBeAg-positive, while others target those who are HBeAg-negative, so testing for this marker is essential for sorting participants into the right groups.

Researchers also check for coinfections with other viruses like hepatitis C, hepatitis D, or HIV, as these can affect how hepatitis B behaves and how treatments work. Some trials exclude people with coinfections, while others are designed to study patients with multiple infections to see how treatments perform under more complex conditions.^[20]

Finally, participants must undergo tests to rule out other causes of liver disease, such as alcohol-related liver damage or autoimmune liver conditions. This ensures that any changes in liver health observed during the trial are due to hepatitis B and the treatment being tested, not other factors.^[7]