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Hepatoma<=> A primary malignant tumour of LIVER cells. It has marked geographical variation, being most common in parts of Africa and the Far East. It is more common in men and with those who have pre-existing CIRRHOSIS.

Hepatolenticular Degeneration<=> See WILSON’S DISEASE.

Hepatocyte<=> The main cell type present in the LIVER. A large cell, it has several important metabolic functions: these include synthesis and storage of biochemical products; detoxi?cation of poisons and unwanted substances; and the manufacture of BILE, the liver secretion that passes through the bile ducts to the small intestine and helps in the digestion of fat.

Hepatitis<=> Otherwise-?t patients under 40 with acute viral hepatitis have a mortality rate of around 0.5 per cent; for those over 60, this ?gure is around 3 per cent. Up to 95 per cent of adults with acute HBV infection recover fully but the rest may develop life-long chronic hepatitis, particularly those who are immunode?cient (see IMMUNODEFICIENCY). Infection is best prevented by good living conditions. HVA and HVB can be prevented by active immunisation with vaccines. There is no vaccine available for viruses C, D and E, although HDV is e?ectively prevented by immunisation against HBV. At-risk groups who should be vaccinated against HBV include: Parenteral drug abusers. Close contacts of infected individuals such as regular sexual partners and infants of infected mothers. Men who have sex with men. Patients undergoing regular haemodialysis. Selected health professionals, including laboratory sta? dealing with blood samples and products.

Hepatitis<=> As well as blood tests to assess liver function, there are speci?c virological tests to identify the ?ve infective agents, and these are important contributions to diagnosis. However, there is no speci?c treatment of any of these infections. The more seriously ill patients may require hospital care, mainly to enable doctors to spot at an early stage those developing acute liver failure. If vomiting is a problem, intravenous ?uid and glucose can be given. Therapeutic drugs – especially sedatives and hypnotics – should be avoided, and alcohol must not be taken during the acute phase. Interferon is the only licensed drug for the treatment of chronic hepatitis B, but this is used with care.

Hepatitis<=> Hepatitis D (HDV) cannot survive independently, needing HBV to replicate, so its sources and methods of spread are similar to the B virus. HDV can infect people at the same time as HBV, but it is capable of superinfecting those who are already chronic carriers of the B virus. Acute and chronic infection of HDV can occur, depending on individual circumstances, and parenteral drug abuse spreads the infection. The disease occurs worldwide, being endemic in Africa, South America and the Mediterranean littoral. Hepatitis E virus (HEV) is excreted in the stools, spreading via the faeco-oral route. It causes large epidemics of water-borne hepatitis and ?ourishes wherever there is poor sanitation. It resembles acute HAV infection and the patient usually recovers. HEV does not cause chronic infection. The clinical characteristics of the ?ve hepatic viruses are broadly similar. The initial symptoms last for up to two weeks (comprising temperature, headache and malaise), and JAUNDICE then develops, with anorexia, nausea, vomiting and diarrhoea common manifestations. Upper abdominal pain and a tender enlarged liver margin, accompanied by enlarged cervical lymph glands, are usual.

Hepatitis<=> •Hepatitis A virus (HAV) is an ENTEROVIRUS which is very infectious, spreading by faecal contamination from patients su?ering from (or incubating) the infection; victims excrete viruses into the faeces for around ?ve weeks during incubation and development of the disease. Overcrowding and poor sanitation help to spread hepatitis A, which fortunately usually causes only mild disease. Hepatitis<=> Hepatitis B (HBV) is caused by a hepadna virus, and humans are the only reservoir of infection, with blood the main agent for transferring it. Transfusions of infected blood or blood products, and injections using contaminated needles (common among habitual drug abusers), are common modes of transfer. Tattooing and ACUPUNCTURE may spread hepatitis B unless high standards of sterilisation are maintained. Sexual intercourse, particularly between male homosexuals, is a signi?cant infection route. Hepatitis C (HCV) is a ?avivirus whose source of infection is usually via blood contacts. E?ective screening of blood donors and heat treatment of blood factors should prevent the spread of this infection, which becomes chronic in about 75 per cent of those infected, lasting for life. Although most carriers do not su?er an acute illness, they must practise life-long preventive measures.

Hepatitis<=> Treatment of cirrhosis is to tackle the underlying cause, to maintain the patient’s nutrition (advising him or her to avoid alcohol), and to treat any complications. The disorder can also be treated by liver transplantation; indeed, 75 per cent of liver transplants are done for cirrhosis. The overall prognosis of cirrhosis, however, is not good, especially as many patients attend for medical care late in the course of the disease. Overall, only 25 per cent of patients live for ?ve years after diagnosis, though patients who have a liver transplant and survive for a year (80 per cent do) have a good prognosis. Autoimmune hepatitis is a type that most commonly occurs in women between 20 and 40 years of age. The cause is unknown and it has been suggested that the disease has several immunological subtypes. Symptoms are similar to other viral hepatitis infections, with painful joints and AMENORRHOEA as additional symptoms. Jaundice and signs of chronic liver disease usually occur. Treatment with CORTICOSTEROIDS is life-saving in autoimmune hepatitis, and maintenance treatment may be needed for two years or more. Remissions and exacerbations are typical, and most patients eventually develop cirrhosis, with 50 per cent of victims dying of liver failure if not treated. This ?gure falls to 10 per cent in treated patients. Viral hepatitis The ?ve hepatic viruses (A to E) all cause acute primary liver disease, though each belongs to a separate group of viruses.

Hepatitis<=> Chronic hepatitis is typi?ed by an invasion of the portal tract by white blood cells (mild hepatitis). If these mononuclear in?ammatory cells invade the body (parenchyma) of the liver tissue, ?brosis and then chronic disease or cirrhosis can develop. Cirrhosis may develop at any age and commonly results in prolonged ill health. It is an important cause of premature death, with excessive alcohol consumption commonly the triggering factor. Sometimes, cirrhosis may be asymptomatic, but common symptoms are weakness, tiredness, poor appetite, weight loss, nausea, vomiting, abdominal discomfort and production of abnormal amounts of wind. Initially, the liver may enlarge, but later it becomes hard and shrunken, though rarely causing pain. Skin pigmentation may occur along with jaundice, the result of failure to excrete the liver product BILIRUBIN. Routine liver-function tests on blood are used to help diagnose the disease and to monitor its progress. Spider telangiectasia (caused by damage to blood vessels – see TELANGIECTASIS) usually develop, and these are a signi?cant pointer to liver disease. ENDOCRINE changes occur, especially in men, who lose their typical hair distribution and su?er from atrophy of their testicles. Bruising and nosebleeds occur increasingly as the cirrhosis worsens, and portal hypertension (high pressure of venous blood circulation through the liver) develops due to abnormal vascular resistance. ASCITES and HEPATIC ENCEPHALOPATHY are indications of advanced cirrhosis.

Hepatitis<=> In?ammation of the LIVER which damages liver cells and may ultimately kill them. Acute injury of the liver is usually followed by complete recovery, but prolonged in?ammation after injury may result in FIBROSIS and CIRRHOSIS. Excluding trauma, hepatitis has several causes: Viral infections by any of hepatitis A, B, C, D, or E viruses and also CYTOMEGALOVIRUS (CMV), EPSTEIN BARR VIRUS, and HERPES SIMPLEX. Autoimmune disorders such as autoimmune chronic hepatitis, toxins, alcohol and certain drugs – ISONIAZID, RIFAMPICIN, HALOTHANE and CHLORPROMAZINE. DISEASE. Acute viral hepatitis causes damage throughout the liver and in severe infections may destroy whole lobules (see below).

Hepatic Encephalopathy<=> A neuropsychiatric syndrome caused by disease of the LIVER, and occurring most often in patients with CIRRHOSIS – see also LIVER, DISEASES OF; it also occurs in acute form in acute failure of liver function. The disorder is believed to be the result of biochemical disturbance of brain function, because the condition is reversible and pathological changes in brain tissue are rarely found. The patient’s intellect, personality, emotions and consciousness are altered but neurological signs may or may not be identi?ed. Apathy, confusion, drowsiness, sometimes CONVULSIONS, speech disturbance and eventually COMA mark the progress of the condition. The principles of treatment are to remove the precipitating causes. These include: URAEMIA; sedative, antidepressant and hypnotic drugs; gastrointestinal bleeding; too much protein in the diet; infection; and trauma (including surgical operations).

Hepatectomy<=> The operation for removal of the LIVER, or part of it.

Heparin<=> Heparin is one of the naturally produced ANTICOAGULANTS with a rapid e?ect, which is thought to act by neutralising thrombin (see COAGULATION). Inactive when taken orally, it is normally given intravenously – it may be given for a few days, combined with an oral anticoagulant such as warfarin, to initiate anticoagulation. Low-dose heparin may be given by subcutaneous injection for longer periods, for the prophylaxis of DEEP VEIN THROMBOSIS (DVT) or PULMONARY EMBOLISM in ‘high-risk’ patients, such as those with obesity or a history of thrombosis, or post-operatively. If haemorrhage occurs, withdrawal of heparin is usually su?cient, but protamine sulphate is a rapidly active and speci?c antidote. Prolonged treatment with heparin may cause osteoporosis (see under BONE, DISORDERS OF).

Henoch-Schönlein Purpura<=> This is an in?ammatory condition of the small blood vessels, the cause of which is not known but may be an allergic response to food or drugs. Most common among young children, the in?ammation causes blood to leak into joints, kidneys, intestine and skin. The child presents with a purpuric rash and stomach pains which may come and go for weeks. Paracetamol alone is often su?cient to alleviate the condition, but severely ill patients may need corticosteroid drugs. All su?erers need follow-up for 12 months to ensure that they have not developed kidney disease.

Henle, Loop of<=> That part of the nephron (see KIDNEYS) between the proximal and distal convoluted tubules. It extends into the renal medulla as a hairpin-shaped loop. The ascending link of the loop actively transports sodium from the lumen of the tube to the interstitium, and this, combined with the ‘counter-current’ ?ow of ?uid through the two limbs of the loop, plays a part in concentrating the urine.

Hemp<=> See CANNABIS.

Hemiplegia<=> PARALYSIS that is limited to one side of the body.

Hemiparesis<=> Paralysis a?ecting the muscles of one side of the body. This most commonly follows a STROKE and occurs when parts of the brain serving motor function on the opposite side of the body are damaged.

Hemimelia<=> This consists of defects in the distal part of the extremities: for example, the absence of a forearm or hand. Hemimelia is a congenital defect; large numbers of cases resulted from the administration of THALIDOMIDE during pregnancy (see also PHOCOMELIA; TERATOGENESIS).

Hemicrania<=> A headache limited to one side of the head. (See also MIGRAINE.)