Liver: Function, failure & disease

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Function
Detoxification
Liver disease
Fatty liver
Enlarged liver
Liver pain
Liver failure
Liver transplant
Things that can harm the liver
Additional resources
Bibliography

The liver is an abdominal glandular organ in the digestive system. It is located in the right upper quadrant of the abdomen, under the diaphragm and on top of the stomach. The liver is a vital organ that supports nearly every other organ to some capacity.

The liver is the body's second-largest organ (skin is the largest organ), according to the American Liver Foundation (ALF), weighing about 3 lbs. (1.4 kilograms). At any given moment, the liver holds about 1 pint (half a liter) of blood — about 13 percent of the body's blood supply, according to Johns Hopkins Medicine.

Production of bile, which helps carry away waste and break down fats in the small intestine during digestion.
Production of certain proteins for blood plasma.
Production of cholesterol and special proteins to help carry fats through the body
Conversion of excess glucose into glycogen for storage (glycogen can later be converted back to glucose for energy) and to balance and make glucose as needed
Regulation of blood levels of amino acids, which form the building blocks of proteins
Processing of hemoglobin for use of its iron content (the liver stores iron)
Conversion of poisonous ammonia to urea (urea is an end product of protein metabolism and is excreted in the urine)
Clearing the blood of drugs and other poisonous substances
Regulating blood clotting
Resisting infections by making immune factors and removing bacteria from the bloodstream
Clearance of bilirubin, also from red blood cells. If there is an accumulation of bilirubin, the skin and eyes turn yellow.

The liver is vital for healthy metabolic function. It metabolizes carbohydrates, lipids and proteins into useful substances, such as glucose, cholesterol, phospholipids and lipoproteins that are used in various cells throughout the body, according to Colorado State University's Department of Biomedical Sciences . The liver breaks down the unusable parts of proteins and converts them into ammonia, and eventually urea.

Alagille syndrome
Alpha 1 anti-trypsin deficiency
Autoimmune hepatitis
Biliary atresia
Cirrhosis
Cystic disease of the liver
Fatty liver disease
Galactosemia
Gallstones
Gilbert's syndrome
Hemochromatosis
Liver cancer
Liver disease in pregnancy
Neonatal hepatitis
Primary biliary cirrhosis
Primary sclerosing cholangitis
Porphyria
Reye's syndrome
Sarcoidosis
Toxic hepatitis
Type 1 glycogen storage disease
Tyrosinemia
Viral hepatitis A, B, C
Wilson disease

Speaking of both conditions, Knowlton said, "Some fat on the liver is normal, but when it starts to accumulate to greater than 5-10 percent, it can lead to permanent liver damage and cirrhosis." It also increases the chance of liver failure or liver cancer. Fatty liver "can be caused by genetics, obesity, diet, hepatitis, or alcohol abuse," said Knowlton. Other risk factors include rapid weight loss, diabetes, high cholesterol, or high trigycerides, according to the ALF.

There may be no symptoms of an enlarged liver, though if they are they are the same as the symptoms for liver disease. Normally, the liver cannot be felt unless you take a deep breath, but if it is enlarged, your doctor may be able to feel it, according to the NIH. The doctor may then do scans, MRIs, or ultrasounds of the abdomen to determine if you have an enlarged liver. Treatment will involve addressing the underlying problem.

Liver pain is felt in the upper right area of the abdomen, just below the ribs. Usually, it is a dull, vague pain though it can sometimes be quite severe and may cause a backache, according to the Cleveland Clinic. Sometimes people perceive it as pain in the right shoulder. It is often confused with general abdominal pain, back pain or kidney pain, according to New Health Guide. It can be hard to pinpoint the exact location or cause of such pains, so it is important to see a doctor. Doctors may do blood tests, ultrasounds or biopsies to determine the cause of pain.

Liver failure is an urgent, life-threatening medical condition. It means that the liver has lost or is losing all of its function. "Livers typically fail gradually," said Knowlton, "but sometimes [it] can be rapid." Early symptoms of liver failure are general, making it difficult to know that the liver is failing. Knowlton said, "Symptoms of liver failure may include nausea, appetite changes, fatigue, diarrhea, jaundice, easy bleeding." As the condition worsens, she said symptoms might include "mental confusion and coma."

"Typical causes of liver failure include Tylenol overdose, viruses, hepatitis B & C, cirrhosis, alcoholism, and some medications," said Knowlton. Georgia's Emory Healthcare stated that there are two types of liver failure: chronic and acute. Chronic liver failure is the most common type of liver failure. It is the result of malnutrition, disease and cirrhosis, and it can develop slowly over years. Acute liver failure is rarer, and it can come on suddenly. Acute liver failure is usually the result of poisoning or a drug overdose, according to the Journal of Clinical Gastroenterology.

Donated livers can come from cadavers or living donors. In the case of living donors, the donor donates part of his or her liver to another person, according to the American College of Gastroenterology. The liver can regrow itself, so both people should end up with healthy, functional livers. According to the National Institute of Diabetes and Digestive and Kidney Diseases the most common reason adults get liver transplants is cirrhosis, though transplants can also be done for patients with various liver diseases or early stage liver cancer.

While some liver diseases are genetic, others are caused by viruses or toxins, such as drugs and poisons. Some risk factors, according to the Mayo Clinic, include drug or heavy alcohol consumption, having a blood transfusion before 1992, high levels of triglycerides in the blood, diabetes, obesity and being exposed to other people's blood and bodily fluids. This can happen from shared drug needles, unsanitary tattoo or body piercing needles, and unprotected sex.

Alcohol is big player in liver damage. It is believed that alcohol could possibly change the type of fungi living in the liver, leading to disease, according to a small study published in the Journal of Clinical Investigation. If this is true, it could lead to new treatment options. The findings suggest that "we might be able to slow the progression of alcoholic liver disease by manipulating the balance of fungal species living in a patient's intestine," study co-author Dr. Bernd Schnabl, an associate professor of gastroenterology at the University of California, San Diego School of Medicine, said in a statement.

Jessie Szalay is a contributing writer to FSR Magazine. Prior to writing for Live Science, she was an editor at Living Social. She holds an MFA in nonfiction writing from George Mason University and a bachelor's degree in sociology from Kenyon College.

With contributions from

Ailsa HarveyContributor

Function

Detoxification

Liver disease

Fatty liver

Enlarged liver

Liver pain

Liver failure

Liver transplant

Things that can harm the liver

Additional resources

Bibliography