The Liver: Vital Functions and Liver Disease
Imagine if your body lacked an internal clean-up crew tasked with scrubbing your blood of toxins at an astonishing rate. Picture what would happen if no onboard chemical factory worked non-stop to produce essential proteins and metabolize nutrients.
For the liver, these core jobs of filtering, producing, processing, and more are all in a day's work - yet its superhero duties often go unrecognized. That is, until disease threatens to compromise its capabilities. Knowledge of the liver's functions and risk factors for illness is the first step to supporting this unsung hero's ongoing mission to maintain wellness from within.
Liver Facts And Stats
Here are some facts and statistics about the human liver[1][2][4]:
Size and Location:
- The liver is the largest solid organ in the body, weighing around 1.8 kg in men and 1.3 kg in women.
- It is roughly the size of a rugby ball and is located in the upper right portion of the abdomen, under the diaphragm, and above the stomach.
Functions:
- The liver carries out over 500 tasks and plays a crucial role in digestion. ● Some of its major functions include detoxification, protein synthesis, and the production of chemicals that aid in food digestion.
- It produces bile, which helps break down and absorb fats, cholesterol, and vitamins in the small intestine.
- The liver metabolizes carbohydrates, stores vitamins, and minerals, filters the blood, and supports blood clotting.
Regeneration:
- The liver is the only visceral organ in the human body that can regenerate. ● It can regrow completely as long as at least 25% of the tissue remains. ● In mice, the removal of two-thirds of the liver leads to complete restoration of liver mass and function within 7-10 days.
- In humans, regeneration can occur in 8-15 days, and the new liver tissue becomes indistinguishable from the original tissue.
Liver Diseases:
- The liver can be affected by various diseases, including cirrhosis, hepatitis, fatty liver disease, and liver cancer.
- Cirrhosis occurs when scar tissue replaces liver cells, leading to liver failure. ● Hepatitis is a general infection of the liver caused by viruses, toxins, or autoimmune responses.
- Fatty liver disease is characterized by the accumulation of fat in liver cells and is often associated with obesity or excessive alcohol consumption.
- Liver cancer, including hepatocellular carcinoma and cholangiocarcinoma, is a significant global health concern.
Key Functions of the Liver
The liver serves over 500 vital functions. Here are some of the liver's most important roles[2][4]:
- Processing nutrients - The liver produces bile to help break down and absorb fats, cholesterol, and fat-soluble vitamins from food. It also stores important vitamins and minerals and releases them into the bloodstream when needed.
- Cleaning the blood - The liver filters 1.4 liters of blood per minute. It removes toxins, waste, excess hormones, and byproducts of medications from the blood to be later excreted.
- Regulating blood sugar - The liver helps balance sugar levels by converting excess sugar into glycogen for storage and converting stored glycogen back into glucose to maintain healthy blood sugar when needed.
- Fighting infections - The liver contains Kupffer cells that destroy bacteria and other harmful substances traveling through the blood and lymph system.
- Metabolizing drugs/alcohol - Enzymes in the liver break down medicines, alcohol, caffeine and natural chemicals so they can be eliminated from the body.
- Manufacturing proteins - The liver produces major proteins needed for blood clotting, fluid balance, transport, and other functions. It makes albumin, the main protein in blood that keeps fluid from leaking into body tissues.
- Aiding digestion - Bile produced by the liver is released into the small intestine to help break down fats, making them easier to absorb. Bile also enables the body to absorb vitamins A, D, E, and K.
Without a functioning liver, none of these vital activities could take place effectively, compromising overall health.
The liver performs over 500 functions, including digestion of proteins, mineral storage, bile production, and blood filtration.
Common Liver Diseases and Conditions
There are over 100 types of liver disease. The most common liver conditions include[5][6]:
- Fatty Liver Disease
- Main cause - fat buildup in liver cells
- Often linked to obesity, high cholesterol, diabetes
- Two types - alcoholic fatty liver disease and nonalcoholic fatty liver disease (NAFLD) ● May progress to steatohepatitis, cirrhosis over time
- Treatment involves lifestyle changes - weight loss, controlling diabetes, low-fat diet 2. Cirrhosis
- Scarring of the liver that prevents proper blood flow
- Causes - fatty liver disease, hepatitis, alcohol abuse
- Symptoms - jaundice, itching, swelling, mental confusion
- Treatment focuses on underlying cause; liver transplant may be needed 3. Hepatitis
- Liver inflammation caused by viruses or other infections
- Types - Hepatitis A, B, C, D, E
- Spread through contact with infected blood or body fluids
- Symptoms - fatigue, nausea, jaundice, fever
- Treatment - antiviral meds, immunotherapy drugs
- Liver Cancer
- Often starts as cancer somewhere else that spreads to liver
- Or may start as uncontrolled growth of liver cells
- Link to hepatitis B, C infections or cirrhosis
- Treatment - radiation, tumor ablation, chemotherapy
Liver Disease Statistics[2][3]:
Prevalence of Liver Disease in the U.S.:
- More than 100 million people in the U.S. have some form of liver disease. ● 4.5 million U.S. adults (1.8% of the population) have been diagnosed with liver disease. ● It is estimated that 80-100 million adults in the U.S. have fatty liver disease, and many are unaware of their condition.
Global Burden of Liver Disease:
- A study published in 2023 reported on the global burden of liver disease. ● The study focused on liver transplantation in Latin America, highlighting the reality and challenges in the region.
- The research provides valuable insights into the current state of liver disease and transplantation.
Burden Of Liver Diseases In The World
Liver diseases pose a significant burden on global health, leading to a substantial number of deaths and causing various complications. Here is an overview of the burden of liver diseases worldwide[2][3]:
Liver Disease Mortality: Liver disease accounts for approximately two million deaths annually, making it responsible for 4% of all deaths worldwide. It is estimated that about two-thirds of all liver-related deaths occur in men.
Liver Cirrhosis: Cirrhosis, a condition characterized by fibrosis and architectural distortion of the liver, is a significant contributor to the burden of liver diseases. Autopsy studies suggest that the global prevalence of cirrhosis ranges from 4.5% to 9.5% of the general population. It is estimated that more than fifty million people worldwide are affected by chronic liver disease. Alcohol, non-alcoholic steatohepatitis (NASH), and viral hepatitis are the most common causative factors for cirrhosis globally.
Alcohol-Related Liver Disease: Alcohol consumption is a major contributor to liver-related deaths worldwide. It accounts for 9.5% of alcohol-related disability-adjusted life years (DALYs) globally. In Europe, alcohol is the main cause of liver-related death, with the highest mortality rates reported in countries like France and Spain. Alcohol is also emerging as the most common cause of chronic liver disease in countries like India.
Non-Alcoholic Steatohepatitis (NASH): The burden of obesity has led to an increase in non-alcoholic fatty liver disease (NAFLD) and its progressive form, NASH. The prevalence of NASH ranges from 6% to 35% globally, with higher rates reported in certain regions. NASH is associated with reduced quality of life, particularly in patients with underlying cirrhosis, diabetes, and obesity.
Other Liver Diseases: Besides alcohol-related liver disease and NASH, there are several other liver diseases that contribute to the burden of liver diseases worldwide. These include cholestatic and autoimmune liver diseases, metabolic liver diseases like hereditary hemochromatosis and Wilson's disease, and hepatocellular carcinoma (HCC).
Key Risk Factors for Liver Damage
Certain behaviors and conditions can seriously impact liver health. Top risk factors include[10]:
- Heavy alcohol use - leads to fatty liver, cirrhosis, liver inflammation
- Obesity - often causes fatty liver disease
- Type 2 diabetes - linked to fatty liver disease
- Exposure to toxins - chemicals, pesticides, over-the-counter meds
- Untreated hepatitis virus infection - causes severe liver inflammation ● Iron or copper overload disorders - leads to cirrhosis over time
Making smart lifestyle choices can go far in preventing liver damage - maintaining healthy weight, avoiding toxins, limiting alcohol, getting vaccinated for hepatitis A and B, practicing safe sex, and taking medications only as prescribed.
Signs of Liver Problems
Many liver conditions do not cause symptoms until extensive damage occurs. Some possible signs include[7]:
- Fatigue, weakness
- Loss of appetite, nausea
- Itching skin
- Jaundice (yellow eyes or skin)
- Swelling in legs or abdomen
- Bruises easily
- Dark urine, pale stool
- Spider-like blood vessels on skin
- Confusion, sleepiness, slurred speech
If these develop, it is important to see a doctor promptly for evaluation. Blood tests and imaging scans can check for liver injury and help pinpoint causes.
Diagnostic Tests for Liver Disease
If liver disease is suspected, doctors use certain tests and procedures to evaluate liver function and determine the cause[8]:
- Blood tests - Check for levels of liver enzymes, bilirubin, proteins and other indicators of liver function and liver injury. Help distinguish different types of hepatitis virus. ● Imaging tests - Ultrasound, CT and MRI scans provide images of the liver, bile ducts, gallbladder to look for tumors, obstruction, etc. Special scans check liver and spleen size, blood flow, blockages.
- Liver biopsy - Small sample of liver tissue examined under microscope for cell changes, fibrosis, viruses, iron/copper content. Considered the definitive way to assess liver health and diagnose disease type. Now often done via a needle guided by imaging rather than through a large incision.
Preventing Liver Disease
Many types of liver disease can be avoided by making smart lifestyle choices and getting medical care when appropriate[11]:
- Maintain healthy weight
- Exercise regularly
- Follow a nutritious, low-fat, low-sodium diet
- Avoid alcohol or drink only in moderation
- Don't smoke; avoid second-hand smoke
- Don't share needles or razors
- Avoid direct contact with blood and body fluids
- Get vaccinated against hepatitis A and B
- Take only necessary medications and OTC meds as prescribed
- Treat conditions like obesity, diabetes, high blood fats
- Seek care if at high risk for viral hepatitis
- Get regular screenings if at increased risk for liver cancer
Being aware of liver health and getting early treatment for any liver abnormalities are also key to preventing progressive liver disease.
Treatment Options for Liver Disease
Treatment options for liver disease vary considerably depending on the specific type, severity, and cause. Some general treatment approaches include[9]:
Medications - Antiviral drugs to treat viral hepatitis; immunosuppressants and corticosteroids to reduce liver inflammation; chemotherapy drugs to slow liver cancer growth; antibiotics to treat liver abscesses. Medications also aim to reduce risk factors like high cholesterol.
Lifestyle changes - Losing weight, improving diet, limiting alcohol intake, and treating diabetes or fatty liver disease through lifestyle steps. Stopping use of certain medications or supplements as needed.
Surgery - Removing cancerous liver tumors; grafting new liver tissue to regenerate healthy cells; draining fluid accumulations; creating surgical bypass of bile duct obstructions. May transplant part of liver from living donor or deceased donor.
Alternative medicine - Some evidence that milk thistle, licorice root and other herbs/supplements may help reduce liver inflammation and protect liver cells. Requires more study.
Seeking prompt treatment is key to halting progressive liver damage. Left untreated, various types of liver disease can lead to serious complications like liver cancer, liver failure, varices, edema, kidney impairment, severe bleeding, coma and death. Paying attention to liver health through regular checkups and making lifestyle changes as needed are vital protective steps.
The Importance of Liver Health
The liver performs absolutely vital functions. It filters waste, manufactures essential proteins, regulates nutrients, maintains normal blood sugar levels, removes toxins, and produces bile to aid digestion. The liver is resilient and can regenerate when injured. However, long-term insults from things like hepatitis viruses, obesity, alcohol abuse, toxic
exposure, genetics, and autoimmune issues can overwhelm the organ’s ability to heal itself.
Taking steps to maintain liver wellness is key to whole-body health. Eating right, staying active, avoiding harmful substances, and getting screened for liver problems can together help this powerhouse organ keep doing its complex and critical work for many years to come.
References:
[1] “Liver Functions, Location, Anatomy and Disease | Columbia Surgery.” Columbiasurgery.org, 2022, columbiasurgery.org/liver/liver-and-its-functions.
[2] Asrani, Sumeet K et al. “Burden of liver diseases in the world.” Journal of hepatology vol. 70,1 (2019): 151-171. doi:10.1016/j.jhep.2018.09.014
[3] “Liver Functionality.” American Liver Foundation, 29 July 2022,
liverfoundation.org/about-your-liver/facts-about-liver-disease/what-does-your-liver-do/. Accessed 2 Jan. 2024.
[4] Kalra, Arjun, et al. “Physiology, Liver.” Nih.gov, StatPearls Publishing, May 2023, www.ncbi.nlm.nih.gov/books/NBK535438/.
[5] “The Stages of Liver Disease - American Liver Foundation.” American Liver Foundation, 9 June 2022, liverfoundation.org/about-your-liver/how-liver-diseases-progress/.
[6] “Liver Disease - NIDDK.” National Institute of Diabetes and Digestive and Kidney Diseases, 2 Jan. 2024, www.niddk.nih.gov/health-information/liver-disease.
[7] “Symptoms of Liver Disease.” British Liver Trust, 19 Dec. 2022,
britishlivertrust.org.uk/information-and-support/liver-health-2/symptoms-of-liver-disease/.
[8] “Diagnostic Testing for Liver Disease | UPMC Center for Liver Diseases.” UPMC | Life Changing Medicine, 2024,
[9] and, Diabetes. “Treatment for Cirrhosis.” National Institute of Diabetes and Digestive and Kidney Diseases, NIDDK - National Institute of Diabetes and Digestive and Kidney Diseases, 2
Jan. 2024, www.niddk.nih.gov/health-information/liver-disease/cirrhosis/treatment. Accessed 2 Jan. 2024.
[10] “Risk Factors - ScotPHO.” Scotpho.org.uk, 2023,
www.scotpho.org.uk/health-conditions/chronic-liver-disease/risk-factors/.
[11] Mehal, Wajahat Z., Francesco Azzaroli, and I. Nicholas Crispe. "Immunology of the healthy liver: old questions and new insights." Gastroenterology 120.1 (2001): 250-260.