Wallach's Interpretation of Diagnostic Tests: Pathways to Arriving at a Clinical Diagnosis (680 page)

   Therapeutic agents (e.g., corticosteroids, trifluoperazine, antilipemic agents, some hyperalimentation)

   Cardiac surgery with cardiopulmonary bypass pump

Normal In

   Inherited metabolic diseases (Dubin-Johnson, Rotor, Gilbert, and Crigler-Najjar syndromes; type I–V glycogenoses, mucopolysaccharidoses; increased in Wilson disease and hemochromatosis related to hepatic fibrosis).

   Consumption of alcohol by healthy persons (in contrast to GGT); may be normal even in alcoholic hepatitis.

   In acute icteric viral hepatitis, the increase is less than two times normal in 90% of cases, but when ALP is high and serum bilirubin is normal, infectious mononucleosis should be ruled out as a cause of hepatitis.

   Limitations

   The elevation in ALP tends to be more marked (more than threefold) in extrahepatic biliary obstruction (e.g., by stone or by cancer of the head of the pancreas) than in intrahepatic obstruction, and it is greater the more complete the obstruction. Serum enzyme activities may reach 10–12 times the upper limit of normal, returning to normal on surgical removal of the obstruction.

   Day-to-day variation is 5–10%.

   Recent food ingestion can increase as much as 30 U/L.

   ALP is 15% and 10% higher in African American men and women, respectively, compared to other racial/ethnic groups.

   Twenty-five percent higher with increased body mass index, 10% higher with smoking, 20% lower with the use of oral contraceptives.

   Common drugs, including penicillin derivatives, antiepileptic drugs, antihistamines, cardiovascular drugs, etc., can increase blood levels.

ALPHA
₁
-ANTITRYPSIN (AAT, ALPHA-1 TRYPSIN INHIBITOR, ALPHA-1 PROTEINASE INHIBITOR)

   Definition