Aldolase (ALS) is a glycolytic enzyme that catalyzes the breakdown of 1,6-diphosphate into triose phosphate. It is found in many body tissues but is most diagnostically significant in disorders of skeletal and cardiac muscle, liver, and pancreas. Three isoenzymes have been identified: A, originating in skeletal and cardiac muscle; B, originating in liver, kidneys, and white blood cells; and C, originating in brain tissue. Isoenzyme C probably lacks diagnostic capability because it does not cross the blood-brain barrier.

• Hepatotoxic drugs, insecticides, and anthelminthics may cause elevated levels.
• Phenothiazines may cause decreased levels.

• Family history of Duchenne's muscular dystrophy:
  • ALS levels rise before clinical signs appear, thus permitting early diagnosis.
• Signs and symptoms of neuromuscular disorders, to differentiate muscular disorders from neurological disorders:
  • Pronounced elevations are seen in clients having Duchenne's muscular dystrophy, polymyositis, dermatomyositis, trichinosis, and severe crush injuries.
  • Decreased aldolase levels are seen in those with late muscular dystrophy, because of loss of muscle cells, or with use of phenothiazines.
  • ALS is not elevated in those with multiple sclerosis or myasthenia gravis, both of which are of neural origin.
• Support for diagnosing other disorders associated with elevated ALS levels:
  • Moderate increases are associated with acute hepatitis, neoplasms, and leukemia.
  • Mild elevations are seen in acute myocardial infarction (peak elevation occurs in 24 hours, with gradual return to normal within 1 week).
• Evaluation of response to exposure to hepatotoxic drugs or chemicals, with liver damage indicated by elevated levels

Nursing Care Before the Procedure

Client preparation is the same as that for any test involving collection of a peripheral blood sample (see Appendix I).

• It is recommended that drugs that may alter test results be withheld for 12 to 24 hours before the test, although this practice should be confirmed with the person ordering the study.

A venipuncture is performed and the sample collected in a red-topped tube. The sample should be handled gently to avoid hemolysis and transported promptly to the laboratory.

Nursing Care After the Procedure

Care and assessment after the procedure are the same as for any study involving the collection of a peripheral blood sample.

• Resume any drugs withheld before the test.
• Abnormal values: Note and report increased levels related to skeletal muscular disorders. Assess for muscle fatigue and strength related to an acute or chronic disorder. Provide energy-saving care to conserve the client's energy while still maintaining as much independence as possible. Instruct in a planned rest and exercise program.