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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.
-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
-primary sclerosing cholangitis
-Predominantly affects young or middle-aged women (10-30 years or > 40 years old)
Symptoms & Signs:
Up to 40% present with acute hepatitis:
-nausea & vomiting
-Right Upper Quadrant pain
and signs of autoimmune disease:
-urticarial rash (a.k.a hives)
-pleurisy (pleuritic chest pain)
-pulmonary infiltration (respiratory symptoms)
The remainder present with an insidious onset:
-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)
-Palmar erythema (reddened palms)
-Gynaecomastia (enlarged male breasts)
-Xanthelasma (fatty deposits around eyes)
-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)
-Scratch marks (from pruritus)
-Ascites (fluid in peritoneal cavity = fluid thrill, shifting dullness)
-Caput medusa (due to portal hypertension)
-Splenomegaly (due to portal hypertension)
-Hepatomegaly, or small liver in later disease
LFTs- ↑Bilirubin, ↑AST, ↑ALT, ↑AlkPhos
↓albumin and ↑prothrombin time in severe disease
Serology- hypergammaglobulinaemia, especially IgG
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.
–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.
-liver cirrhosis and associated complications:
-hepatocellular carcinoma- so check AFP tumour marker twice yearly
-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