Laboratory tests in digestive systema Klinika Gastroenterologii Dr n. med. Małgorzata Pujanek

Laboratory tests Bilirubin total – incerased causes jaundice

Bilirubin direct = conjugated bilirubin If direct bilirubin is normal – the problem is an excess of uncojugated bilirubin; the location of the problem is upstream of bilirubin conjugation in the liver (hemolysis, viral hepatitis, cirrhosis) If it is elevated – the liver is conjugating bilirubin normally, but is not to excrete it (bile duct obstruction, gallstones, cancer) It is always implies liver or biliary tract disease

Albumin Albumin – a protein made specificaly by the liver, the main of total protein The levels decreased in chronic liver disease (cirrhosis) – usually reflects severe liver damage and decreased albumin synthesis Consequences of low albumin - edema

Alanine aminotransferas ALT – liver cells It is found primarily in the liver It is a more specific indicator of liver injury

Aspartate aminotransferas AST – associated with liver parenchymal cells It is raised in acute liver demage (elewated parameter is not specific for liver demage) AST and ALT are not greatly elevated in obstructive jaundice

AST/ALT AST/ALT elevation instead of ALP favor liver cell necrosis (mechanism over cholestatis) AST and ALT both > 1000 the normal amount – acetaminaphen toxicity, shock,fulminant liver failure AST and ALT both >3x of normal amountbut not >1000 – alcohol toxicity, viral hepatitis, drug induced,liver cancer, sepsis > 3:1 highly suggestive of alcoholic liver disease

ALP – alkaline phosphatase ALP – enzyme in the cell lining the biliary ducts of the liver It rises with large bile duct obstruction, interhepatic cholestasis, infiltrative diesases It is also higher in growing children (presents in bone and placental tissue) 2-3x higher It is not helpful in distinguishing between intrahepatic and extrahepatic cholestasis

GGTP -  -glutamyl transpeptidase less sensitive marker for cholestatic damage than ALP (is fount in or near the bile canalicular membrane of hepatocytes May be elevated with even minor, subclinical levels of liver disfunction Is raised in chronic alcohol toxicity It is elevated in cholestasis

Coagulation test The liver is responsible for the production of coagulation factors INR (internal normalized ratio) –measures the speed of a particular pathway of coagulation INR will be increased only if the liver is so damaged that synthesis of witamin K- dependent coagulation factors has been impaired It is not a sensitive measure of liver function

Prothrombin time It is used to determine the clotting tendency of blood, liver damage, witamin K status

A liver function test can be usd to determine if a patient’s bile ducts are being blocked by an unknown obstruction (tumor)

Liver test in hepatobiliary disorders type of disorders bilirubinAST AlAT ALPalbuminProthrombin time hemolysis Gilbert syndrome normal to 5mg/dl 85% due to indirect fraction No bilirubinuria normal acute hepatocellular necrosis both may ↑ bilirubinuria ↑ > 500 IU AlAT>AST normal to<3x normal elevation normalusually normal chronic hepatocellular disorders both may ↑ bilirubinuria ↑ but <300 IUnormal < 3xoften ↓prolonged alcoholic hepatitis cirrhosis both may ↑ bilirubinuria AST:ALT > 2normal <3xoften ↓prolonged intra- and extrahepatic cholestasis (obstractive jaundice) both may ↑ bilirubinuria normal rarely >500 IU ↑, often 4xnormal, unles chronic normal infiltrative diseases (tumor) usually normalnormal to slighy↑↑, often 4xnormal