Wallach's Interpretation of Diagnostic Tests: Pathways to Arriving at a Clinical Diagnosis (860 page)

   Muscle atrophy of neurologic origin (e.g., old poliomyelitis, polyneuritis)

   PA

   Most malignancies

   Scleroderma

   Acrosclerosis

   Discoid lupus erythematosus

   Limitations

   Following MI, CK activity increases 4–8 hours after acute onset, activities peak at 12–36 hours, and usually returns to normal activities in 3–4 days. Although total CK has been used as a diagnostic tool for MI detection, along with CK-MB, it has been predominantly replaced with troponin I or T due to lack of myocardial specificity.

   Exercise and muscle trauma (contact sports, traffic accidents, IM injections, surgery, convulsions, wasp or bee stings, and burns) can elevate serum CK values.

   To distinguish myoglobinuria from hemoglobinuria, serum CK and LD may be helpful. CK is normal with uncomplicated hemolysis, but LD and LD-1 usually are increased.

CREATINE KINASE ISOENZYMES (CK-BB, CK-MM, CK-MB)
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   Definition

   Creatine kinase is an enzyme consisting of three major isoenzymes, CK-BB (brain), CK-MB (heart) (see p. 901), and CK-MM (skeletal muscle). CK-BB is rarely present. It has been described as a marker for adenocarcinoma of the prostate, breast, ovary, colon, and GI tract, and for small cell anaplastic carcinoma of the lung. CK-BB has been reported with severe shock and/or hypothermia, infarction of bowel, brain injury, stroke, as a genetic marker in some families with malignant pyrexia, and with MB in alcoholic myopathy. CK-MM is found in normal serum.

   Use