Wallach's Interpretation of Diagnostic Tests: Pathways to Arriving at a Clinical Diagnosis (1039 page)

   To monitor tumor activity involving anemias and lung cancer

   Liver and renal disease

   After AMI (the use of LDH for MI detection has been replaced by cardiac troponins.)

   Marker for hemolysis, in vivo (e.g., hemolytic anemias) or in vitro (artifactual)

   Interpretation

Increased In

   
Cardiac diseases

   AMI. Increases in 10–12 hours, peaks in 48–72 hours (approximately three times normal). Prolonged elevation over 10–14 days was formerly used for late diagnosis of AMI; now replaced by C-troponins. An LD reading >2,000 IU suggests a poorer prognosis. An LD-1/LD-2 ratio >1 (“flipped” LD) may also occur in acute renal infarction, hemolysis, some muscle disorders, pregnancy, and some neoplasms.

   CHF: LD isoenzymes are normal, or LD-5 may be increased due to liver congestion.

   Insertion of intracardiac prosthetic valves consistently causes chronic hemolysis, with increase of total LD, LD-1, and LD-2. This is also often present before surgery in patients with severe hemodynamic abnormalities of cardiac valves.

   Cardiovascular surgery: LD is increased ≤2 times normal without cardiopulmonary bypass and returns to normal in 3–4 days; with extracorporeal circulation, it may increase ≤4–6 times normal; this increase is more marked when the transfused blood is older.

   Increases have been described in acute myocarditis and RF.

   
Liver diseases

   Cirrhosis, obstructive jaundice, and acute viral hepatitis show moderate increases.