Common GI Conditions

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Hepatitis B

What is Hepatitis B? 

Hepatitis B virus infection predominantly affects the liver. It affects an estimated 257 million people worldwide, including 2% of the population in South-east Asia¹, and 3.6% of Singapore residents aged 18-79 years².


What causes it and how is it transmitted? 

Hepatitis B virus is transmitted by exposure of infected blood to broken skin or mucous membranes. Before universal neonatal vaccination, ‘vertical transmission’ from mother to child during childbirth was a common cause. Other possible ways transmission can occur include sexual contact; use of non-sterile instruments which have been in contact with infected blood such as razors, toothbrushes, needles used for tattoos or piercing, medical and dental equipment; as well as unscreened and infected blood transfusions.

What problems can hepatitis B infection cause? 

If not identified, treated or monitored, hepatitis B may lead to acute or chronic progressive liver injury, resulting in liver scarring and hardening (fibrosis, cirrhosis and its related problems), liver failure, as well as liver cancer.

Rarely, hepatitis B can cause non-liver related problems, such as inflammation of blood vessels (vasculitis) or of the kidneys (glomerulonephritis).

What are the symptoms? 

Acute hepatitis B in adulthood more often result in symptoms – such as abdominal discomfort, loss of appetite, nausea, lethargy, or jaundice – however, the infection is more likely to spontaneously settle.

Exposure to hepatitis B in the neonatal or childhood periods are usually asymptomatic – but the infection is more likely to become chronic (i.e a long-term, persistent infection), which may lead to the aforementioned problems in the long term. A significant number of people with chronic hepatitis B infection are unaware of their status.

When should I get checked?

If you develop symptoms of hepatitis B, or if there is a history of hepatitis B in your family or sexual contacts, you should have your hepatitis B status checked.

Evaluation for Hepatitis B is also recommended as part of sexual health checks; pregnancy antenatal checks; before the commencement of immune system suppressing medications such as chemotherapy for cancers; or if you have had previous exposure to aforementioned risk factors of transmission.

Hepatitis B testing can be done by your primary care doctor (polyclinic or GP) via blood tests. These can show whether you have a current infection, previous exposure, and/or immunity.

If I have hepatitis B, what other tests will I need? 

If you have hepatitis B, your doctor will refer you to a gastroenterologist who may arrange a further evaluation with:

  1. Blood tests to check for the amount of virus in your blood; the current phase of your infection; any evidence of liver inflammation; other blood-borne virus and immunity screening (hepatitis C and HIV exposure, hepatitis A immunity);
  2. Imaging tests such as an ultrasound to check the appearance of your liver
    3) Measurements of the amount of liver scarring that has accumulated over time, via blood tests, liver stiffness measurements (elastography) or liver biopsy.

Chronic infection with hepatitis B can also predispose to liver cancer, and regular screening with ultrasound and blood tests will likely be recommended – tailored to your risks, such as age, ethnicity, family history, virus level and extent of liver damage.

What treatments are available? 

Not everyone with hepatitis B needs treatment, so you should see a gastroenterologist find out. If therapy is indicated, currently the two types are:

  1. Pegylated interferon injections, which boost the immune system with the hope to control hepatitis B infection;
  2. Oral medication tablets called “nucleotide/nucleoside analogues”, which suppress hepatitis B virus replication and minimise related injury.

How can I prevent Hepatitis B? 

Hepatitis B vaccination with subsequent immunity demonstrated by antibody levels in your blood test will confer protection to hepatitis B. This is particularly important for immediate family members, household or sexual contacts of persons who have hepatitis B. If your blood tests show immunity related to previous exposure, you may not require vaccination.

How do I look after my Hepatitis B? 

Avoid alcohol, as it can cause and compound liver damage. Hepatitis A vaccination or blood test to check the presence of immunity can likewise prevent additional liver injury if you are ever exposed to this infection.

If you are on therapy, especially tablet medication for hepatitis B, compliance is of utmost importance, as discontinuation of medication may lead to rebound flare of virus count and severe – potentially life-threatening – liver injury.

Regular follow up with your doctor is important to monitor the progress of your hepatitis B, as well as screening to allow early detection and treatment of liver cancer.


1 World Health Organization. Global Hepatitis Report 2017.
2 Ang LW et al. Seroepidemiology of hepatitis B virus infection among adults in Singapore: a 12-year review. Vaccine. 2013 Dec 17;32(1):103-10.