Wallach's Interpretation of Diagnostic Tests: Pathways to Arriving at a Clinical Diagnosis (903 page)

   Increased ALP in liver diseases (due to increased synthesis from proliferating bile duct epithelium) is the best indicator of biliary obstruction but does not differentiate intrahepatic cholestasis from extrahepatic obstruction. In cholestasis, ALP level is increased out of proportion to other liver function tests.

   Increases before jaundice occurs.

   High values (greater than five times normal) favor obstruction and normal levels virtually exclude this diagnosis.

   Markedly increased in infants with congenital intrahepatic bile duct atresia but is much lower in extrahepatic atresia.

   
Increased 10 times normal:
carcinoma of the head of the pancreas, choledocholithiasis, and drug cholestatic hepatitis.

   
Fifteen to twenty times increase:
primary biliary cirrhosis, primary or metastatic carcinoma.

   Increase (3–10 times normal) with only slightly increased transaminases may be seen in biliary obstruction and converse in liver parenchymal disease (e.g., cirrhosis, hepatitis); increased greater than three times normal in <5% of acute hepatitis.

   Increased (2–10 times normal; usually 1.5–3 times increase) serum ALP and LD in early infiltrative (e.g., amyloid) and space-occupying diseases of the liver (e.g., tumor, granuloma, abscess).

   Increase less than three to four times normal is nonspecific and may occur in all types of liver diseases (e.g., congestive heart failure, infiltrative liver diseases, cirrhosis, acute [viral, toxic, alcoholic] or chronic hepatitis, acute fatty liver).

   
Increased five times normal:
infectious mononucleosis, postnecrotic cirrhosis.

   Increased ALP (of liver origin) and LD with normal serum bilirubin, AST, and ALT suggest obstruction of one hepatic duct or metastatic or infiltrative disease of the liver.

   GGT/ALP ratio >5 favors alcoholic liver disease.

   Isolated increase of GGT is a sensitive screening and monitoring test for alcoholism. Increased GGT due to alcohol or anticonvulsant drugs is not accompanied by increased ALP.