Finding HBsAg (hepatitis B surface antigen) positive on a blood test is an important finding suggesting that the person is infected with the hepatitis B virus (HBV).
But a positive HBsAg on its own does not allow the conclusion “I have chronic hepatitis B”, “my liver has been damaged” or “I need to start medication straight away.”
A positive HBsAg matters; but to understand what stage the infection is at, it has to be weighed together with other tests.
What is HBsAg?
HBsAg is the hepatitis B surface antigen. Finding HBsAg in the blood suggests that the hepatitis B virus is present in the body.
HBsAg can be positive both in acute hepatitis B infection and in chronic HBV infection. So a single HBsAg result cannot tell you whether the infection has just started or has been going on for a long time.
Does a positive HBsAg mean I have chronic hepatitis B?
Not always.
HBsAg can also be positive during a newly acquired acute hepatitis B infection. HBsAg remaining positive for longer than six months is one of the main criteria for chronic HBV infection.
So in someone with a first positive result, previous tests and the other necessary HBV markers should be assessed.
Which tests are done if HBsAg is positive?
When a positive HBsAg is found, looking at HBsAg alone is not enough to understand the person’s infection status. Where your doctor thinks it necessary, tests such as the following may be used:
- Anti-HBc total
- Anti-HBc IgM
- HBeAg
- Anti-HBe
- HBV DNA
- ALT and AST
- Bilirubin
- Albumin
- INR
- Full blood count and platelets
Assessment for other viral hepatitides may also be needed.
Why does HBV DNA matter?
HBV DNA shows how much of the hepatitis B virus’s genetic material is in the blood. In other words, it gives information about how far the virus is replicating.
HBV DNA is one of the important tests in:
- Assessing the disease
- Deciding whether treatment is needed
- Following patients on treatment
But the HBV DNA value is not on its own enough to decide about treatment either.
Why do ALT and AST matter?
ALT and AST are enzymes that give information about whether liver cells are being affected. ALT in particular matters in assessing chronic hepatitis B. However:
- A normal ALT does not mean hepatitis B is of no consequence.
- A raised ALT does not on its own show how far the disease has progressed.
The results have to be weighed together with HBV DNA and the other findings.
How is the state of the liver assessed?
In people with a positive HBsAg, the structure of the liver and the degree of fibrosis are assessed where needed. For this, the following may be used:
- Ultrasound
- Elastography (measurement of liver stiffness)
- Blood-test-based assessments of fibrosis
Other investigations may be needed in selected situations.
The aim is not only to show that the virus is present, but to determine whether — and how far — the liver has been affected by it.
Does everyone with a positive HBsAg need medication?
No.
Not everyone with a positive HBsAg needs antiviral treatment straight away. The decision to treat is made by weighing the HBV DNA level, the ALT level, the state of fibrosis or cirrhosis in the liver, the person’s age and their other clinical features.
Some people need treatment; others can be kept under regular follow-up.
The thought “I am not on medication, so my condition is unimportant” is not correct. Regular follow-up matters in patients who do not need treatment too.
What does “I am a hepatitis B carrier” mean?
In the past, the phrase “healthy carrier” was often used for people who were HBsAg positive with normal liver enzymes and low viral activity.
Today it is understood that hepatitis B has different clinical phases, and a person’s situation is assessed together with HBV DNA, ALT, HBeAg and the liver findings.
For this reason it is not right to go for many years without any check-up on the grounds of simply “being a carrier”.
How is hepatitis B transmitted?
HBV can be transmitted through infected blood and some body fluids. The main routes are:
- From mother to baby during birth
- Contact with infected blood
- Unprotected sexual contact
- Non-sterile needles or medical/cosmetic instruments
- Sharing personal items that may be contaminated with blood
Is it transmitted by everyday contact?
Hepatitis B is not transmitted by ordinary social contact such as eating at the same table, hugging, shaking hands, being in the same room, coughing or sneezing.
There is no need for people with a positive HBsAg to be kept apart from social life.
Which personal items should not be shared?
Personal items that may come into contact with blood should not be shared:
- Razors
- Shaving blades
- Toothbrushes
- Nail clippers
What should family members do?
Household members and the sexual partner of a person found to be HBsAg positive should be assessed for hepatitis B.
For those without immunity, the hepatitis B vaccine is an extremely effective form of protection.
Can I have the hepatitis B vaccine?
In a person with confirmed HBsAg positivity, the hepatitis B vaccine does not treat the existing infection. The vaccine is given mainly to protect people who are not infected with hepatitis B.
This is why assessing the immune status of family members in particular matters.
Does a positive HBsAg matter in pregnancy?
Yes.
HBV DNA levels should be assessed in pregnant women who are HBsAg positive. Because there is a risk of transmission to the baby during birth, the pregnancy and delivery should be planned appropriately.
Giving the baby the hepatitis B vaccine at the right time after birth and, where needed, hepatitis B immune globulin (HBIG), is extremely important in preventing transmission.
In some pregnant women with high HBV DNA levels, antiviral treatment in the later stages of pregnancy may also come into consideration.
Can I drink alcohol?
In people with hepatitis B infection, alcohol can increase liver damage. It is therefore best avoided.
You should also tell your doctor about the medicines, herbal products and supplements you take. Being “natural” or “herbal” does not mean a product is harmless to the liver.
Does a positive HBsAg turn into cancer?
A positive HBsAg does not mean cancer.
But over the years chronic hepatitis B can, in some people, increase the risk of fibrosis → cirrhosis → liver cancer. This risk is not the same for everyone.
This is why regular follow-up in suitable patients and, where needed, screening for hepatocellular carcinoma matter.
When is urgent assessment needed?
In someone with a positive HBsAg, seek medical care without delay if there is
New and obvious jaundice · severe or persistent vomiting · confusion or excessive sleepiness · rapidly increasing swelling of the abdomen · vomiting blood · black, tarry stools · obvious gastrointestinal bleeding.
What should you do if HBsAg is positive?
- Do not panic. A positive HBsAg does not on its own mean there is serious damage to your liver.
- Do not ignore the result. Whether the infection is acute or chronic, and the state of the liver, need assessing.
- Find your previous tests. Earlier HBsAg, ALT, AST and HBV DNA results can be very valuable.
- Tell your family. Testing close contacts for hepatitis B and, where needed, vaccinating them, matters.
- Do not take medicines or herbal products on your own. Whether treatment is needed is decided by medical assessment.
- Do not abandon regular check-ups. Follow-up may be needed even in people who do not need treatment.
Remember
- A positive HBsAg calls for assessment for hepatitis B infection.
- On its own it does not mean chronic hepatitis or cirrhosis.
- HBsAg remaining positive for longer than six months matters for chronic HBV infection.
- HBV DNA gives information about how far the virus is replicating.
- Not everyone with a positive HBsAg has to take medication.
- Family members and partners should be tested and, if not immune, assessed for vaccination.
- Follow-up matters even when treatment is not needed.
This is not enough to make a diagnosis
A positive HBsAg has to be weighed together with HBV DNA, ALT/AST, the other hepatitis B markers, the state of fibrosis in the liver and the person’s clinical features.
If your HBsAg result is positive, rather than diagnosing yourself as a “carrier”, with “chronic hepatitis” or with “cirrhosis”, the right course is proper medical assessment.
Sources
- Prof. Ali Tüzün İnce, MD