Autoimmune Hepatitis

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Autoimmune Hepatitis (AIH)

Definition: an inflammatory liver disease of unknown cause characterised by suppressor T-cell defects with autoantibodies directed against hepatocyte surface antigens.

Classification, types I-III, is by autoantibodies.

Aetiology/risk factors:

-cause unknown but hepatotropic viruses (e.g. measles, herpes) and some drugs appear to trigger AIH in genetically predisposed individuals.

-associated with HLA-A1, HLA-B8 & HLA-DR3

Associated conditions:

-pernicious anaemia

-ulcerative colitis

-glomerulonephritis

-autoimmune thyroiditis

-autoimmune haemolysis

-diabetes mellitus

-primary sclerosing cholangitis

Epidemiology:

-Predominantly affects young or middle-aged women (10-30 years or > 40 years old)

Symptoms & Signs:

Up to 40% present with acute hepatitis:

-fever

-anorexia

-jaundice

-nausea & vomiting

-diarrhoea

-Right Upper Quadrant pain

and signs of autoimmune disease:

-fever

-malaise

-urticarial rash (a.k.a hives)

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-polyarthritis

-pleurisy (pleuritic chest pain)

-pulmonary infiltration (respiratory symptoms)

-glomerulonephritis (haematuria)

The remainder present with an insidious onset:

-gradual jaundice

-malaise

-fatigue

-anorexia

-weight loss

-nausea

-epistaxis (nose bleeds)

-amenorrhoea (lack of periods) is common and disease tends to attenuate during pregnancy.

or are asymptomatic and diagnosed incidentally with signs of chronic liver disease.

 

Signs of Chronic Liver Disease:

-Leukonychia (due to low albumin)

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-Clubbing

-Palmar erythema (reddened palms)

-Dupuytren’s contracture

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-Spider naevi

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-Gynaecomastia (enlarged male breasts)

-Xanthelasma (fatty deposits around eyes)

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-Atrophic testes

-Loss of body hair

-Parotid enlargement (enlargement of the parotid salivary gland)

-Asterixis (a.k.a hepatic flap- large flapping tremor of hands when wrists are extended = sign of hepatic encephalopathy = decompensated liver disease)

-Easy bruising

-Jaundice

-Scratch marks (from pruritus)

-Ascites (fluid in peritoneal cavity = fluid thrill, shifting dullness)

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-Caput medusa (due to portal hypertension)

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-Splenomegaly (due to portal hypertension)

-Hepatomegaly, or small liver in later disease

Investigations:

Bloods-

LFTs- ↑Bilirubin, ↑AST, ↑ALT, ↑AlkPhos

           ↓albumin and ↑prothrombin time in severe disease

Serology- hypergammaglobulinaemia, especially IgG

                  +ve antibodies

Type I-+ve ASMA in 80%. +ve ANA in 10%. ↑IgG in 97%.

(Seen in 80%. Typically females <40 yrs. Good response to immunosuppression in 80%. 25% have cirrhosis at presentation.)

Type II- +ve LKM1

               –ve ASMA, -ve ANA

(Commoner in Europe than USA, and in children. More commonly progresses to cirrhosis, less treatable.)

Type III- +ve anti-SLA or anti-LP antigen

                –ve ASMA, -ve ANA

=antismooth muscle antibodies (SMA), antinuclear antibodies (ANA), antiliver/kidney microsomal type antibodies (LKM1), antibodies against soluble liver antigen (SLA), liver-pancreas antigen (LP)

FBC- anaemia, ↓white cells, ↓platelets = hypersplenism (from portal hypertension)

Liver biopsy- needed to make diagnosis

-mononuclear infiltrate (macrophages and lymphocytes) of portal and periportal areas and piecemeal necrosis +/- fibrosis.

Cirrhosis on biopsy = worse prognosis.

MRCP- helps to exclude PSC if alkaline phosphatase is disproportionately elevated. PSC would show a ‘beaded’ appearance of bile ducts due to strictures.

Diagnosis depends on excluding other diseases + criteria based on IgG levels, autoantibodies, and histology in the absence of viral disease.

Management:

Immunosuppression:

Prednisolone (30mg/d PO 1 month, decrease by 5mg a month to maintenance dose of 5-10mg/d PO)- can sometimes be stopped after 2 years but relapse in 50-86%.

Azothioprine (50-100mg/d PO)- may be used as steroid sparing agent to maintain remission.

Budesonide- corticosteroid with low systemic toxicity due to high first-pass metabolism. Can be used e.g. in non-cirrhotic AIH, to partly amiolarate the side effects of prednisolone and azothioprine.

-Hepatitis A and B vaccinations

-Ultrasound and AFP level every 6-12 months in cirrhosis patients to monitor for hepatocellular carcinoma,

⇒Liver transplantation is indicated for decompensated cirrhosis or if there is failure to respond to medical therapy, but recurrence may occur.

Complications:

-liver cirrhosis and associated complications:

-jaundice

-encephalopathy

-ascites

-variceal bleeding

-hepatocellular carcinoma- so check AFP tumour marker twice yearly

-osteoporosis

-hyperlipidaemia

-fulminant hepatic failure

-complications of drug therapy

Prognosis: 10 year survival after presentation is about 80%, lower if there is cirrhosis at presentation (62%).

With immunosuppression, remission is achievable in 80% of patients within 3 years.

References: Cheese & Onion, Rapid Medicine

 

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