22nd July 2023

Hepatitis

Hepatitis refers to inflammation of the liver. It is a condition with a variety of aetiologies, including infectious causes, autoimmune disease, and drugs. This topic will focus on infectious causes of hepatitis and drug-induced hepatitis; autoimmune hepatitis is covered in the Chronic Liver Disease topic.

Viral hepatitis 

There are five forms of hepatitis viruses: A, B, C, D, and E. The most important clinically are hepatitis A, B and C. A and E cause acute infections, whereas B, C and D can cause both acute and chronic forms of hepatitis, and in the latter is a key cause of chronic liver disease in the UK and worldwide. The key information for each virus is summarised in the table below.

Viral hepatitis may be asymptomatic. The clinical features of acute infection include abdominal pain (especially in the right upper quadrant), jaundice, nausea and vomiting, malaise and fatigue. Chronic infection is associated with constitutional symptoms like weight loss, malaise and fatigue, as seen in chronic liver disease – and if it progresses can cause cirrhosis and liver failure. There are specific antiviral treatments for hepatitis B and C (see below), and if chronic infection does progress into chronic liver disease, then this is managed accordingly. Hepatitis C is also strongly associated with hepatocellular carcinoma as a complication.

Hepatitis B and C are a particular public health concern amongst intravenous drug users and sex workers. These demographics, as well as those with an occupational risk, such as healthcare workers, are targeted with screening and vaccination programmes.

Table 2: Summary of different causes of viral hepatitis

Hepatitis B serology

This refers to the serological testing of various antigens and antibodies for hepatitis B, which can be used to distinguish acute and chronic infection, and establish immunity. Questions on hepatitis B serology are common in MRCP examinations, so it is important to know this topic well.

The serological markers tested for are the two antigens of HBsAg and HBeAg, and two antibodies of anti-HBs, and anti-HBc (both IgM and IgG forms).

HBsAg is the first marker to appear, and it triggers anti-HBs production. HBsAg implies acute disease, but if it persists longer than six months, it indicates chronic infection. The detection of anti-HBs indicates immunity, either through exposure or vaccination. It will be negative in chronic infection as immunity has not developed. Anti-HBc is a marker of previous or current infection; IgM antibodies indicate acute or recent (within the last six months) infection, whereas IgG antibodies indicate previous infection.

A vaccinated person will have anti-HBs antibodies but not anti-HBc antibodies, as they have not been previously infected. This is therefore used to establish whether immunity has been caused by infection or vaccination.

The presence of HBeAg indicates a patient is infectious and could hence pass on the virus.

Vaccination

Vaccination for at-risk individuals and groups is a key part of the management strategy for viral hepatitis. Vaccinations exist for hepatitis A and B, but not for C or D. Some vaccinations exist for hepatitis E, but they are not very effective.

In the UK, hepatitis A and B vaccinations are offered as travel vaccinations, to people with chronic liver disease, high risk occupations, men who have sex with men, and intravenous drug users.

Drug-induced hepatitis

Also known as drug-induced liver injury (or DILI), this is an important cause of hepatitis. People with pre-existing liver disease and a history of alcohol excess are at increased risk. DILI is generally categorised by the type of damage caused to the liver, divided into hepatocellular and cholestatic (though the latter group may also cause a mixed picture). The causative drugs are summarised in the table below.

Methotrexate, methyldopa and amiodarone are also associated with a separate risk of liver cirrhosis.

Table 3: Categorisation of drug-induced liver injury

Treatment is of cessation of the causative drug, then supportive treatment of any acute symptoms and chronic long-term complications.