Sunday, November 11, 2012

Hepatitis: Liver disease


ACUTE HEPATITIS:

There is hepatic inflammation and may be viral, autoimmune, chemical, drug, etc. The hepatic picture shows:
i.              Pronounced rise in AST, ALT >1000 U/L
ii.            Moderate increase in ALP. But sometimes after hepatitis patient may enter cholestatic phase heralded by rising ALP and GGT.
iii.     Bilirubinuria and hyperbilirubinaemia detectable as jaundice (when bilirubin > 40-50 µmol/L).

Aminotransferase start rising before the onset of sign (hyperbilirubinemia) and symptoms. They fall with the onset of jaundice and normalize (AST before ALT) at same time plasma bilirubin increases. So, unless jaundice develops patients are unaware of presence of acute hepatitis. Persistence of symptoms, signs and/or abnormal liver tests (particularly increased aminotransferases) for more than 6 months constitutes chronic hepatitis.

Chronic hepatitis can progress to acute liver failure characterized by elevated plasma aminotransferases, increased PT/INR and development of encephalopathy.

Differential diagnosis of hepatitis:

First is to distinguish viral hepatitis and non viral hepatitis. Alcoholic hepatitis plasma aminotransferases are not grossly raised and in this condition a ratio of AST: ALT >2 is characteristic, while in other cause of hepatitis it is <2.

ACUTE LIVER FAILURE:

Hepatic dysfunction within 6 month of onset of liver disease constitute acute liver failure. There is hepatic encephalopathy and prolonged and persistent increase in PT. If this occurs within 2 month of first symptom, the condition is called fulminant hepatic failure. The causes may be paracetamol overdose, hepatitis B and E, Wilson disease, hepatic malignancy, etc.

Laboratory features:

Serology for detection of viral antigen and antibodies. There is hepatic picture. There is coagulation defect as indicated by protracted PT. Hypoglycemia due to impaired glycogenolysis and gluconeogenesis. Hyperbilirubinemia produces false low creatine values and thus precipitation of bilirubin and plasma protein is required for creatinine measurement.


CHRONIC HEPATITIS:

Persistence of clinical or biochemical features (hepatic picture, but increase in aminotransferase is only 2-10 times URL) of liver disease for more than 6 month constitute chronic hepatitis. There is prolonged PT and moderate or severe hypoalbuminemia Differential diagnosis of chronic hepatitis

Viral hepatitis:

Hepatitis B: HBsAg, IgM against HBV core antigen HBc

Hepatitis C: Anti-HCV IgM; HCV-RNA by PCR

In viral hepatitis ALT level increases 5-10 times during antigenemia and declines after antigen clearance. Antigen clearance is followed by increase in antibodies and acute hepatic illness called hepatic flare.

Thyroid function test in viral hepatitis a longitudional follow up study after and before administration of interferon and relation to dose.

Alcoholic hepatitis:

Blood alcohol, GGT, MCV, Desialylated transferrin

Wilson’s disease:

Low ceruloplasmin, high tissue (liver) copper and urinary copper, low ALP, AST. Presence of ocular Kayser-Fleischer rings.

PRIMARY BILIARY CIRRHOSIS:

This is chronic cholestatic condition in which there is destruction of bile ducts. There is characteristic cholestatic picture, increase in ALP, increase in conjugated bilirubin and decrease in albumin. Antimitochondrial antibodies are detected in 95% of the cases. 
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