ASPARTATE AMINOTRANSFERASE, ALANINE AMINOTRANSFERASE, AND LACTIC DEHYDROGENASE ELEVATION
ASPARTATE AMINOTRANSFERASE, ALANINE AMINOTRANSFERASE, AND LACTIC DEHYDROGENASE ELEVATION: Excerpt from Differential Diagnosis in Primary Care
When the chemistry profile shows an elevation of these enzymes, recall the tissues that produce a large amount of these enzymes: the liver, heart, and skeletal muscles. This translates into hepatitis, myocardial infarction, and dermatomyositis as the principal conditions to consider in the differential diagnosis. When only the aspartate aminotransferase (AST) level is elevated, liver disease is the primary consideration. When only the lactate dehydrogenase (LDH) level is elevated, pulmonary infarction should be high on the list of possibilities and a lung scan should be ordered. CHF may also produce a significant elevation of the AST with little or no elevation of the LDH.

ASPARTATE AMINOTRANSFERASE (AST)(SGOT), ALANINE AMINOTRANSFERASE (ALT), AND LACTIC DEHYDROGENASE (LDH) ELEVATION
Approach to the Diagnosis
Obviously, the first condition to rule out is myocardial infarction. This is done by ordering serial MB-CPKs (MB isoenzyme of creatine phosphokinase) and ECGs. Serum cardiac troponin levels may also be helpful. Next, determine if the patient is on heparin, because this may elevate the alanine aminotransferase (ALT) level. Various muscle diseases (dermatomyositis, muscular dystrophy, muscle trauma, etc.) may be excluded by ordering CPK enzymes also, particularly the MM (MM isoenzyme of creatine phosphokinase) fraction. Liver disease can be revealed through by a liver profile, CT scan of the abdomen, and gallbladder ultrasonography.
Other Useful Tests
- CBC
- Urinalysis
- Sedimentation rate (neoplasm, dermatomyositis)
- Repeated chemistry profile (myocardial infarct, muscle disease)
- Serum amylase level (pancreatitis)
- Lung scan (pulmonary infarct)
- Electromyogram (dermatomyositis, muscle disease)
- ANA analysis (dermatomyositis)
- Muscle biopsy (collagen disease, muscular dystrophy)
- Liver biopsy
Book Source Details
- Book Title: Differential Diagnosis in Primary Care
- Author(s): R. Douglas Collins
- Year of Publication: 2007
- Copyright Details: Differential Diagnosis in Primary Care, Copyright © 2007 Lippincott Williams & Wilkins.
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