The liver is an organ with many vital functions. It’s involved in digesting food, processing toxins and medications, and distributing nutrients to the body.1 Liver disease refers generally to the variety of diseases that can affect the liver.2
Most conditions discussed in this article cause chronic (long-term) liver disease. Some result in acute (short-term) or acute-on-chronic illness.3-4 Liver disease represents a group of common conditions that are important to understand, identify, and prevent. Liver disease in children also has unique considerations.
The Centers for Disease Control and Prevention (CDC) estimates that 4.5 million people, or 1.8 percent of the US population, are diagnosed with chronic liver disease or cirrhosis.5 It’s estimated that as many as 80 million people have liver disease without knowing it.14
This group of conditions is the ninth leading cause of death in the US. Globally, chronic liver disease (CLD) caused 1.37 million deaths in 2017 and was more common in men than women.6 Improved prevention and treatment for viral hepatitis has decreased liver-related deaths in recent years.
Acute liver failure (ALF) is rarer than chronic liver disease, causing illness in less than 0.001 percent of people in high-income countries.7 However, ALF from viral hepatitis remains a significant risk in lower-income countries.
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Symptoms, Signs, and Stages of Liver Disease
Symptoms and signs of liver disease depend on the timing (acute vs. chronic) and stage of the condition.
Symptoms can be nonspecific (shared with other diseases) and vary based on the disease stage.8 Liver disease is divided into four stages9-10:
- Hepatitis (liver inflammation): Some inflammation in the liver is healthy, but when it becomes a problem, it’s referred to as hepatitis.
- Fibrosis (scarring): Scarring or stiffening occurs in chronic liver disease due to long-term hepatitis and results from high levels of collagen (connective tissue protein) buildup.
- Cirrhosis (severe scarring): Permanent damage to the liver caused by severe scarring.
- Liver Failure: When the liver fails, it’s not performing vital functions. Liver failure can result from acute (usually happening within days11) or chronic (progressing over years through the four stages) liver disease and usually requires a liver transplant.
Hepatitis causes a range of symptoms and signs9:
- Swelling of the belly
- Changes in urine color (usually dark)
- Fatigue (low energy)
- Itchy skin
- Joint pain
- Low appetite
- Malaise (a general feeling of discomfort) and lethargy (severe lack of energy)
- Jaundice (yellow skin and eyes)
If you have mild-to-moderate liver disease with fibrosis, you likely won’t notice any symptoms.9 Instead, these symptoms are more common in people with cirrhosis and are discussed in another article.
Acute Liver Failure
Acute liver failure starts with symptoms of acute liver injury.11 These symptoms are similar to those of hepatitis and then worsen:
- Hepatic encephalopathy, which refers to11:
- Flapping hands when arms are held up
- Coma (unconsciousness)
- Fluid buildup in the belly
- Swelling of the arms and legs
- Blood clotting issues
Hepatic encephalopathy may initially show up as a change in personality, forgetfulness, changes in sleep patterns, and irrational or violent behavior.11
Chronic Liver Failure
Chronic liver failure (CLF) symptoms result from long-term cirrhosis.12 When people develop symptoms of CLF, they have decompensated cirrhosis. Symptoms include:
- Fluid buildup in the belly
- Hepatic encephalopathy
- Bleeding from the stomach or intestines
The symptoms of liver cancer can look like other illnesses and usually don’t show up until later stages of the disease.13 In someone with a history of liver disease or who has risk factors, these symptoms and signs may point to liver cancer:
- Unintentional weight loss
- Decreased appetite
- Feeling full after a small meal
- Nausea or vomiting
- An enlarged liver (mass under the ribs on the right side)
- An enlarged spleen (mass under the ribs on the left side)
- Belly pain
- Swelling of the belly
- Itchy skin
Causes of Liver Disease and Risk Factors
There is a fair amount of overlap between risk factors for and causes of certain liver conditions. However, a risk factor is not always a cause. The most common risk factors for developing liver disease are also the most common causes of it:
- Alcohol use: Research shows a major increase in the risk of developing liver disease in people who drink alcohol, especially for those who drink heavily for many years.15 Alcohol use causes liver disease by increasing steatosis (fat storage in the liver). Steatosis leads to inflammation and death of liver cells.19
- High amounts of body fat: The liver stores more fat in people with more body fat, causing disease in some cases.16
- Metabolic conditions: These include dyslipidemia (high cholesterol, triglycerides), hypertension (high blood pressure), and diabetes
- Viral infection: Several viruses increase the risk of liver disease and directly cause it. Long-term inflammation from the body fighting infection causes liver disease.20
The following factors increase the risk of developing liver disease but are not known to cause it directly:
- Cigarette smoking: Smoking cigarettes increases the risk of developing liver cancer.17
- Certain gene changes passed down through family members increase the risk of developing liver disease.17-18
- IV drug use: Injecting drugs into the blood increases the risk of contracting viruses that can cause liver disease.13
- Aflatoxin B1: Exposure to foods containing aflatoxin B1 (a poison that can grow on foods that are kept in humid places) increases the risk of liver cancer, most commonly in sub-Saharan Africa, southeast Asia, and China.17
Types of Liver Disease
Liver disease shows up differently depending on the cause. Knowing the unique characteristics of each type helps to find the right treatment. Here are the most common types of liver disease in adults.
Viral hepatitis can be acute or chronic.20 The viruses that cause it are hepatotropic viruses (viruses that target liver cells directly, named hepatitis A through E), Epstein-Barr virus, herpes simplex virus, and cytomegalovirus. Most deaths from this type of liver disease are caused by chronic hepatitis B and C.
Alcohol-Associated Liver Disease
There are three stages of alcoholic liver disease, starting with steatosis, progressing to hepatitis, and then cirrhosis.19 Once cirrhosis develops, hepatocellular carcinoma (liver cancer) may follow. Alcohol-associated liver disease is one of the leading causes of liver disease in the United States, along with nonalcoholic fatty livery disease, or NAFLD.
NAFLD (Nonalcoholic fatty liver disease)
Nonalcoholic fatty liver disease (NAFLD) is defined as the buildup of fat in at least 5 percent of liver cells without another cause for it.21 NAFLD includes NAFL (nonalcoholic fatty liver disease) and NASH (nonalcoholic steatohepatitis). NASH is characterized by inflammation caused by fat buildup in the liver. NASH can lead to fibrosis, cirrhosis, and hepatocellular carcinoma. NASH can be related to high body fat percentage and metabolic conditions such as diabetes, high blood pressure, hyperlipidemia (high cholesterol and triglycerides) toxin exposure, or drugs.
The two known types of autoimmune hepatitis (Type 1 and Type 2) are defined by the presence of certain antibodies in your blood.23 Antibodies are proteins made by the immune system to attack foreign substances. Autoimmune hepatitis may result from a combination of genetic risk, environmental triggers, and low immune system response. This leads to inflammation and fibrosis of the liver.
Primary Biliary Cholangitis (PBC)
PBC is a chronic liver disease where small bile ducts (tubes that carry bile through the liver to the gallbladder to store or to the first part of the intestines for digestion) inside the liver are inflamed.24 Over time, the ducts are destroyed, bile builds up in the liver, and liver function suffers.25 The exact cause isn’t known, but research points to genetics and certain triggers that cause the immune system to attack bile ducts.
Primary Sclerosing Cholangitis (PSC)
Primary sclerosing cholangitis (PSC) is a chronic liver disease that also affects bile ducts.26 In PSC, bile ducts within and outside the liver are inflamed and become scarred, causing bile buildup in the liver and liver damage. Like PBC, the cause of PSC isn’t known.27 Research suggests that genetics, immune system issues, bacterial changes in the gut, and injury to bile ducts may be involved.
Hemochromatosis is a disorder that causes a harmful buildup of iron in the body from absorbing too much iron from the diet.28 The body needs a certain amount of iron to make red blood cells, muscle, and heart cells. However, when the body has too much, it can cause organ damage. Certain genetic mutations cause hemochromatosis.29
Alpha-1 Antitrypsin (AAT) Deficiency
Alpha-1 Antitrypsin (AAT) deficiency is a genetic disorder caused by low production of alpha-1 antitrypsin protein.30 AAT protein protects the body from an enzyme that is released by white blood cells during infection. Without this protein, the enzyme attacks lung cells, causing lung disease. The dysfunctional AAT protein can also accumulate in the liver, causing liver disease.
Drug-Induced Liver Injury (DILI)
Some medications, herbals, vitamins, supplements, and drugs can cause liver damage.
Diagnosis and Testing of Liver Disease
Diagnosing liver disease starts with a detailed history and exam completed by a doctor.31 A doctor will ask questions about your symptoms and complete an exam looking for signs of liver disease. They will also ask about medical and family history, looking for conditions that increase the risk of liver disease.
Blood Testing for Liver Disease
Because early liver disease is usually asymptomatic, testing is usually needed to make a diagnosis. When liver disease is a concern, certain blood tests are ordered8:
- Liver tests: Measure liver enzymes (proteins that speed up chemical reactions in the body), such as albumin, aspartate transaminase (AST), alanine transaminase (ALT), alkaline phosphatase (ALP), or bilirubin (a substance produced in the spleen when blood cells are broken down and processed by the liver). A common test of liver function is the international normalized ratio (INR) test, which measures your blood’s clotting ability, which relies in part on a liver-produced protein called prothrombin.
- Fibrosis blood tests: Combines multiple lab tests to provide a general idea of the level of fibrosis in the liver.
- Viral tests: Used to identify viral infections, including hepatitis A through E, cytomegalovirus (CMV), and Epstein-Barr virus.
- Iron studies: Measure the level of iron and related proteins in the body, which can help diagnose hemochromatosis.
- Autoimmune tests: Used to identify autoimmune hepatitis, PBC, and PSC.
- Alpha-1 antitrypsin: Measures the protein affected in AAT deficiency to diagnose this condition.
Imaging Tests for Liver Disease
Imaging is another important part of diagnosing liver disease.8
- Ultrasounds (US): US images are created by passing sound waves through a part of the body. US of the abdomen (belly) is one of the most common initial tests used to characterize liver disease. US shows the size and amount of fibrosis or scarring of the liver to help diagnose cirrhosis.
- Computed tomography (CT) and magnetic resonance imaging (MRI): CT scans use multiple X-rays to image internal organs. CTs can show liver tumors/masses or blockage in the bile ducts. MRI uses magnets to image the liver and is better than CT at diagnosing cancer, hemochromatosis, and steatosis.35
- Transient elastography (TE or fibroscan): This is a special type of ultrasound. TE is used to diagnose early cirrhosis by measuring how high-speed sound waves move through the liver. The waves move faster through stiffer tissue, helping to identify a scarred liver.
- Liver biopsy: A biopsy takes a small piece of tissue from the liver to look at under a microscope. It’s used in situations where your doctor suspects liver disease and wants to confirm it, or for a more specific assessment of how damaged the liver is.32 Biopsies can be taken through the skin, through the belly in a surgical procedure, or through a neck vein.8
Complications of Liver Disease and Effects on the Body
Some liver diseases, like infection with hepatitis A, can cause short-lived illness that has no long-term effects.33 However, liver disease usually causes chronic illness.8 Chronic liver disease can affect organs other than the liver, especially when liver function suffers significantly. The most common complications of liver disease are portal hypertension, hepatocellular insufficiency, and hepatocellular carcinoma, as described below.
Portal hypertension is high blood pressure in the vein that feeds blood to the liver.8 When a liver becomes scarred, the blood has a harder time moving through it, creating high pressure in blood vessels. The most common cause of portal hypertension is cirrhosis. Symptoms of this condition include:
- Swelling in the blood vessels of the esophagus and stomach
- Swelling in the veins around the belly button
- Swelling in the rectal veins
- Fluid buildup in the belly
Anytime blood vessels get swollen, they are more likely to bleed or cause pain. Importantly, ascitic fluid (fluid buildup in the belly) can become infected and cause spontaneous bacterial peritonitis (SBP). This complication of liver disease is life-threatening and treated with intravenous antibiotics.
Hepatocellular insufficiency means that liver cells are not functioning normally.8 Liver cells are important for detoxification. When liver cells aren’t working, harmful substances like ammonia (a substance made when proteins break down) can build up. High levels of ammonia in the blood leads to confusion, abnormal movements, and loss of consciousness. Because the liver makes important proteins, other problems can occur, such as bleeding and clotting.
Hepatocellular Carcinoma (HCC)
Hepatocellular carcinoma (HCC)—the fifth most common cause of cancer worldwide—develops in people diagosed with cirrhosis at a rate of about 1.5% annually.22,23 The types of liver diseases that cause HCC are hepatitis B and C, alcoholic liver disease, and NAFLD/NASH.
Prevention of Liver Disease
In cases where someone has a genetic liver disease, prevention may not be possible. However, many of the liver diseases discussed here can be prevented with the right strategies35:
- Eat a balanced diet with fruits, vegetables, and healthy (unsaturated) fats
- Exercise regularly
- Avoid alcohol
- Take medications as prescribed
- Screen for hepatitis B and C
- Treat related conditions, like diabetes, hepatitis B and C, and NASH
- Get the hepatitis B vaccine
Resources for Living with Liver Disease
If you or a loved one is living with liver disease, there are many resources that can support you. Look at these resources to get started: