The human liver is a large, reddish-brown organ in the upper right abdomen, weighing about three pounds in the average adult. It is the largest solid organ in the body. The term “liver disease” encompasses a wide range of conditions that can affect this organ and disrupt its many functions. Understanding the liver’s role is the first step in appreciating the impact of these diseases.
The Role of the Liver
The liver performs over 500 tasks. One of its primary jobs is to filter blood from the digestive tract before it passes to the rest of the body. This process removes toxins, byproducts of metabolism, and other harmful substances like alcohol and drugs. The liver then chemically modifies these substances, making them less harmful for excretion.
Another function of the liver is metabolism, where it plays a central part in processing nutrients from the small intestine. The liver converts carbohydrates, proteins, and fats into forms the body can use for energy or store for later. For instance, it stores excess glucose as glycogen and releases it into the bloodstream when energy is needed, regulating blood sugar levels.
The liver is also a production powerhouse. It produces bile, a fluid needed for digesting fats in the small intestine. It also synthesizes proteins for blood plasma, such as albumin, which maintains fluid balance in the circulatory system, and fibrinogen, which is necessary for blood clotting.
Finally, the liver acts as a storage depot for various vitamins and minerals. It holds reserves of fat-soluble vitamins A, D, E, and K, as well as vitamin B12. The liver also stores iron, derived from the breakdown of old red blood cells, in a form called ferritin, keeping it ready for the production of new red blood cells.
Common Types of Liver Disease
Liver diseases are categorized by their underlying causes, ranging from viral infections to genetic predispositions. One category is infectious hepatitis, which is inflammation of the liver from a viral infection. Hepatitis A is an acute illness spread through contaminated food or water. Hepatitis B and C can cause chronic infections, are transmitted through infected body fluids, and are significant causes of long-term liver damage.
Fatty liver disease is another prevalent condition, characterized by the accumulation of excess fat in liver cells. This condition is divided into two main types. Alcohol-associated liver disease (AALD) is caused by heavy alcohol consumption. Nonalcoholic fatty liver disease (NAFLD) is not related to alcohol use and is linked to metabolic conditions like obesity, type 2 diabetes, and high cholesterol. Both forms can progress to more severe liver damage.
Some liver diseases arise from a misdirected immune system. In these autoimmune conditions, the body’s immune cells mistakenly attack liver cells. Autoimmune hepatitis is one such example, causing inflammation and liver damage. Another is primary biliary cholangitis (PBC), where the immune system destroys the small bile ducts within the liver, leading to bile buildup and liver cell injury.
Genetic factors can also be the root cause of certain liver diseases. These inherited conditions involve the abnormal accumulation of substances that are toxic to the liver. Hemochromatosis leads to an excessive buildup of iron in the body, including the liver. Wilson’s disease is a similar condition involving the accumulation of copper, which can cause significant damage to the liver and other organs if not treated.
Many chronic liver diseases can ultimately lead to cirrhosis. Cirrhosis is an advanced stage of liver scarring, known as fibrosis, not a disease in itself. This scarring is the result of long-term damage to the liver from conditions like chronic hepatitis, fatty liver disease, or autoimmune disorders. The scar tissue replaces healthy liver tissue, disrupting the liver’s structure and impairing its function.
In some cases, chronic liver disease can lead to the development of liver cancer. The most common type of primary liver cancer is hepatocellular carcinoma, which often arises in individuals who already have chronic liver conditions, particularly cirrhosis. The persistent inflammation associated with these conditions can create an environment where cancerous cells are more likely to develop.
Signs and Symptoms
The presentation of liver disease can vary, and in the early stages, there may be no noticeable symptoms. When symptoms do appear, they often reflect the liver’s diminished capacity. One of the most characteristic signs is jaundice, a condition that causes the skin and the whites of the eyes to turn yellow. This occurs due to a buildup of bilirubin, a yellow pigment from red blood cell breakdown that a damaged liver cannot properly clear.
Fatigue is a very common symptom of liver disease. Individuals may also experience discomfort in the upper right abdomen, where the liver is located. As liver function declines, fluid can accumulate in the abdomen, a condition known as ascites, leading to swelling and a feeling of fullness. Fluid retention can also cause swelling, or edema, in the legs and ankles.
Changes in the color of urine and stool can also indicate liver issues. Urine may become dark brown or orange, while stools may appear pale, clay-colored, or even black and tarry. These changes are related to the liver’s role in processing bilirubin. Other symptoms can include a loss of appetite, unexplained weight loss, and persistent nausea or vomiting.
A compromised liver can also affect the body’s ability to clot blood, as it produces many of the necessary clotting factors. This can result in a tendency to bruise or bleed more easily, such as frequent nosebleeds or bleeding from the gums. These symptoms warrant medical attention, especially when they occur in combination.
Diagnosis and Medical Evaluation
Diagnosing liver disease begins with a medical history and physical examination. To confirm a diagnosis and assess the extent of liver damage, physicians use a combination of tests. Blood tests are often the first step. Liver function tests (LFTs) measure the levels of certain enzymes and proteins in the blood. Elevated levels of enzymes like ALT and AST can indicate liver inflammation, while levels of proteins like albumin and bilirubin provide insight into liver function.
If blood tests suggest a problem, imaging tests are used to get a visual of the liver. An ultrasound is a common, non-invasive technique that uses sound waves to create pictures of the liver, revealing information about its size, shape, and texture. For more detailed images, a computed tomography (CT) scan or a magnetic resonance imaging (MRI) scan may be ordered. These can provide cross-sectional views to identify scarring or other abnormalities.
In some cases, a liver biopsy may be necessary for a definitive diagnosis and to determine the severity of liver damage. During this procedure, a small sample of liver tissue is removed with a thin needle. The tissue sample is then examined under a microscope by a pathologist. This examination can reveal the specific type of liver disease, the degree of inflammation, and the extent of any scarring.
Management and Prevention Strategies
The management of liver disease depends on the specific type and stage of the condition, but lifestyle modifications are a common thread. A balanced diet, regular physical activity, and maintaining a healthy weight are foundational for liver health. For individuals with fatty liver disease, these changes can sometimes reverse the condition in its early stages. Limiting or avoiding alcohol is also a standard recommendation, as it is toxic to liver cells.
Vaccination offers a powerful tool for preventing certain types of liver disease. Vaccines are available to protect against Hepatitis A and Hepatitis B, two viral infections that can cause liver inflammation. The Hepatitis B vaccine is important as chronic Hepatitis B is a leading cause of cirrhosis and liver cancer. These vaccines are recommended for individuals at increased risk and are part of routine childhood immunizations.
For diagnosed liver conditions, various medications may be prescribed. Antiviral drugs can be used to manage and, in some cases, cure chronic Hepatitis C, as well as to suppress the Hepatitis B virus. For autoimmune liver diseases, medications that suppress the immune system can help reduce inflammation. Other medications may be used to manage the symptoms and complications of advanced liver disease, such as diuretics to reduce fluid retention.
In situations where liver disease has progressed to end-stage liver failure, a liver transplant may be the only viable treatment option. This surgical procedure involves replacing the diseased liver with a healthy liver from a deceased donor or a portion from a living donor. Liver transplantation can be a life-saving measure for individuals with irreversible liver damage.