The liver is the largest, heaviest and most complex internal organ in the body, weighing 1-1.5kg and hidden mostly by the lower right ribcage. Its shape is determined by the cavity available in the upper right part of the abdomen, between the diaphragm and the rib margin. It is one of only two organs1 to have two blood supplies, receiving blood from the hepatic arteries [20%] and the portal vein [80%] (carrying blood from the intestines). The liver makes and breaks down proteins, sugars and fats; stores nutrients absorbed from the intestines; and removes toxins from the blood. It is the powerhouse, recycling and disposal plant of the body. Life literally is not possible without the liver.
There are many causes of liver disease, including alcohol, viral hepatitis2 (for example Hepatitis B, C3 and the glandular fever virus EBV4), autoimmune diseases, poisons/drugs (for example an overdose of paracetamol, some antibiotics, and drugs) and inherited disorders. Hepatitis A never causes chronic problems or cirrhosis. The most common cause in Western countries is alcohol - worldwide it is Hepatitis B (often transmitted from mother to foetus).
The Liver's Normal Function
The liver receives the blood from the gut after a meal and turns sugar (glucose) into glycogen (a storage molecule). This is turned back into glucose when required, keeping blood glucose levels stable. There is only so much 'storage space' - once that is filled, the rest is converted to fat. Excess carbohydrates and protein are also converted into fat. Fat can be broken down into sugar again, for example: exercising burns off calories.
The liver also makes proteins (mostly blood proteins for example clotting factors and albumin, and hormones) and bile acids (essential for fat digestion and vitamin absorption). The breakdown of haemoglobin, cholesterol and proteins all occur at least partly in the liver. Digested proteins in the form of amino acids are broken down further in the liver, a process known as deamination.
Water-soluble toxins and waste products can be eliminated via the kidneys in the urine, but non-water soluble toxins need to be chemically modified by the liver to allow this process to occur. The liver also eliminates chemicals not produced by the body.
The Diseased Liver
The initial response of the liver to disease is inflammation and fatty change. Inflammation can be caused by contact with toxic substances such as bufotoxin, so care should be taken when handling/disposing of a creature like the Cane Toad.
Heavy drinking will cause alcoholic hepatitis. Prolonged or severe inflammation leads to cirrhosis (scarring of the liver). When a section of liver is removed the liver will regenerate, but scarring in cirrhosis stops this regeneration and so the damage is irreversible. The most obvious sign of liver disease is jaundice, where the skin and whites of the eyes are yellow.
Neonatal jaundice is very reversible: the current treatment is increased fluids and UV light therapy.
Other symptoms include constant, extreme tiredness and lack of energy; itching; nausea; pain to the right shoulder; and pain in the right upper area of the abdomen. The complications of liver cirrhosis include: lack of albumin causing swollen legs and abdomen; lack of clotting factors causing easy bruising and internal haemorrhages (haematomas); impaired mental state from low-blood sugar and toxins (acting like morphine and sleeping tablets) normally removed by the liver; and cancer of the liver (hepatoma).
Another malfunction of the liver is the inability to breakdown LDL (low density lipoprotein) cholesterol, and statins5 need to be taken to keep LDL at a safe level to prevent arterial disease, known as atherosclerosis. If a clot forms and blocks a narrowed artery, it can cause a heart attack or stroke. LDL cholesterol is the harmful (bad) cholesterol, as opposed to the HDL (high-density lipoprotein) cholesterol which is absorbed and used as energy etc.
The only current treatment for liver failure is transplantation. Death usually occurs from infection of a suppressed immune system, or vomiting blood from abnormal vessels in the oesophagus (varices). With drugs, the liver combines cocaine and alcohol and creates a toxic third substance, cocaethylene, which magnifies cocaine's euphoric effects. The mixture of cocaine and alcohol is the most common two-drug combination which results in drug-related death, the second being paracetamol and alcohol (this is usually an attempt at suicide and if it fails the patient will almost certainly have long-term liver damage).
Liver disease is often first detected because of abnormal liver blood tests, often called liver function tests (LFTs), although they are not actually a measure of liver function. Abnormal albumin, and blood clotting tests, demonstrate abnormal liver function. The pattern of the abnormalities of LFTs points to whether the problem is the liver, a haemolytic anaemia, or the biliary system. Blockage of the biliary system6 and haemolytic anaemias7 cause jaundice as well.
Blood tests can diagnose viral hepatitis and autoimmune liver diseases. Iron and copper levels in blood tests check for iron overload (haemachromatosis) and copper overload (Wilson's disease), both inherited diseases that can cause cirrhosis. An ultrasound scan will show blockage of the bile duct, fatty liver, cirrhosis and liver tumours. A liver biopsy may be necessary to examine the liver under the microscope, look for iron or copper, or determine the amount of virus present.
The main aim of treatment of liver disease is to prevent cirrhosis. Obviously alcohol consumption must stop. Both Hepatitis B and C can be treated with antiviral drugs. Where the patient's immune system is attacking the liver, powerful suppressants of the immune system are given. N-acetylcysteine is given to prevent damage from paracetamol overdoses. Iron or copper overload can be treated with chelating agents that help the body to eliminate the excess heavy metals.
Treatment of cirrhosis involves preventing complications (eg drugs to prevent bleeding from varices); ensuring good nutrition, and monitoring for liver cancer. Water tablets (chemical diuretics) for the treatment of fluid retention in the legs (peripheral oedema) or abdomen (ascites) should not be taken without medical consultation, particularly if the patient is already taking other medication. The current prescription drug for water retention, Bendroflumethiazide, lowers blood-pressure; and lists as potential side effects: mineral changes in body salts; feeling physically sick; loss of appetite; feeling dizzy or light-headed on standing up; feeling weak, tired, drowsy or sleepy; confusion; and muscle cramps. It can cause gout, impotence, skin rash, itchy skin and allergic reactions.
Laxatives (usually a syrupy solution called lactulose) need to be administered to prevent constipation and to reduce the chances of the poisonous substances from the bowel bypassing the liver and reaching the brain, causing drowsiness, confusion and coma (hepatic encephalopathy).
For someone recovering from any form of liver disease, it is very important to minimise the amount of fat in the diet: eating bread without any form of butter or margarine; frying eggs in a non-stick pan without any fat, etc.
Liver as a food product contains considerable amounts of vitamin D. However as it is a filter for toxins, it can also contain amounts of less desirable substances.
Although liver and liver products, such as pâté and liver sausage, are good sources of iron, they can also contain very high concentrations of vitamin A8. If taken in excess, this vitamin can build up in the liver and cause serious harm to a growing foetus. As a result, the Department of Health advises all pregnant women to avoid eating liver and liver products.