Cholestasis reflected in abnormal bilirubin and AP levels In acute bile duct obstruction from a gallstone, AST and ALT levels often reach 500 U per L or more in the first hours, whereas AP and GGT levels can take several days to rise. MARKERS OF CHOLESTASIS
Elevation of GGT alone results from enzyme induction by alcohol or aromatic medicatios GGT is elevated in persons who drink 3 or more per day
Direct/conjugated hyperbilirubinemia Conjugated bilirubin levels do not rise until the liver has lost approximately half of its excretory ability. The presence of conjugated bilirubin in the urine ( urine dipstick), is always indicative of hepatobiliary disease.
Indirect/uncongealed Hyperbilirubinemia: Gilbert syndrome Common benign inherited disorder Levels between 2 and 3 mg/d Patients develop detectable jaundice during acute illness or starvation
Hemolysis Confirmed by an elevated retic count & increased haptoglobin levels. In adults, no serious liver disease will cause elevation of indirect bili alone without a concurrent rise in direct bili levels.
AP Elevated levels are found in adolescents, children (secondary to bone growth), and pregnant women Women with persistently elevated AP levels primary biliary cirrhosis Confirmed by a serum antimitochondrial antibody test
Hepatic Cause of elevated AP Hepatocellular disease (usually <3-fold increase) Alcoholic hepatitis Viral hepatitis Fatty infiltration of liver Cirrhosis
Hepatic Cause of elevated AP Obstructive processes (usually >3-fold increase) Choledocholithiasis Cancer of head of pancreas Cholangiocarcinoma Cholestatic hepatitis
Hepatic Cause of elevated AP Infiltrative, neoplastic, Primary or metastatic carcinomas (15- to 20-fold increase) Primary biliary cirrhosis Amyloidosis Hepatic congestion caused by heart disease Infectious mononucleosis
Hepatic Cause of elevated AP Medications: Captopril Erythromycin Gold salts Phenothiazines Trimethoprimand-sulfamethoxazole Anticonvulsants
Increased synthesis of AP in Diabetes mellitus 44% of patients with DM have increased AP
Common Non hepatic Causes of Elevated GGT Acetaminophen overdose Acute myocardial infarction Acute pancreatitis Anticonvulsants (phenytoin, phenobarbital, carbamazepine)
Albumin An Index of liver synthetic capacity Low albumin level and no other LFT abnormalities are likely to have a non hepatic cause
Albumin Non hepatic causes of low Albumin: Inflammatory states such as burns, trauma, & sepsis Active rheumatic disorders Severe end-stage malnutrition Pregnancy Proteinuria
PT Does not become abnormal until more than 80%of liver synthetic capacity is lost Useful to be followed in acute hepatic failure (Factor 7 has very short half life)
PT Vitamin K deficiency Chronic cholestasis or fat malabsorption A trial of vitamin K injections ( 5 mg /day SQ x 3 days) practical way to exclude vitamin K deficiency PT should improve within a few days
Ammonia Concentrations are much higher in the brain than in the blood and therefore do not correlate well It is not unusual for the blood ammonia to be normal in a patient who is in a coma from hepatic encephalopathy.
QUIZ Other than hepatitis, causes of elevated serum GGT include all of the following except: A. Diabetes mellitus. B. Hypothyroidism. C. Brain tumor. D. Infectious mononucleosis. E. Acute myocardial infarction
Answer : B Hyperthyroidism is associated with elevated GTT
QUIZ The greatest increase in serum alkaline phosphatase is generally seen in a patient with which of the following conditions? A. Primary biliary cirrhosis. B. Alcoholic hepatitis. C. Viral hepatitis. D. Fatty infiltration of the liver. E. Cancer of the head of the pancreas