Aldolase level, and Its Significance

Sample

1. It is done on the Serum of the patient.
2. Patients should fast for 8 hours before giving the sample.
   1. Take 3 to 5 ml of blood in the disposable syringe. Keep the syringe for 15 to 30 minutes and then centrifuge for 2 to 4 minutes. Can get a clear serum.
3. Avoid hemolysis and separate serum immediately.
4. It is stable for:
   1. 8 hours at room temperature.
   2. 4 °C for 5 days.
   3. -15 °C for 15 days.

Precautions

1. The previous muscular injection may increase the aldolase level.
2. Hemolysis and exposure to chlorinated insecticide may increase the level.
3. Hepatotoxic drugs may increase the level.
4. The phenothiazine may decrease the aldolase level.

Indications

1. This test is indicated when inflammatory diseases of the muscles (myopathy) are suspected.
2. To assess the severity of the myopathy.
3. Other tests like Lactate dehydrogenase, Creatinine Phosphokinase, and Aspartate transferase are advised and are helpful for the diagnosis, So this test is no more recommended.

Pathophysiology

1. Definition of the aldolase enzyme:
   1. Aldolase is a glycolytic enzyme that splits fructose-1,6-phosphatase into two triose phosphate molecules in the metabolism of glucose.
2. Aldolase is present in all tissue like the brain, kidneys and prominent in skeletal and heart muscles.
3. Aldolase enzyme is present in the cell and the nucleus.
   

   Aldolase functions and distribution

4. It converts sugar to energy.
5. Aldolase described in different forms like:
   3. Aldolase A occurs in most of the tissue.
   4. Aldolase B is seen in the liver and kidneys.
6. This is a glycolytic enzyme, and it cleaves fructose 1,6 – bisphosphate into dihydroxyacetone phosphate and glyceraldehyde 3 – phosphate.
   

   Aldolase biochemical reaction

7. This has the main interest in the primary disease of skeletal muscles.
8. If the muscle disease is due to neurological causes then aldolase will be normal.
9. Clinical significance:
   1. The major use of aldolase is for the diagnosis of rhabdomyolysis.
      5. CPK is also raised, and this is more sensitive and specific, so aldolase is not recommended.
   2. This is greatly increased in the Duchenne-type pseudo hypertrophic muscle dystrophy compared to other muscular diseases.
   3. It is high in the early stage.
   4. But it falls as the disease progresses.
      1. There is a 10 to 15 times increase than the normal level.
   5. This is raised in dermatomyositis and limb-girdle dystrophy.
      1. Normal values are seen in poliomyelitis, myasthenia gravis, and multiple sclerosis, where the origin of the muscle disease is neurogenic.
   6. It is usually normal in cirrhosis and obstructive jaundice.
10. Aldolase pattern is like ALT, and it comes to normal in 10 to 15 days.
    

    Aldolase changes in the blood

Normal

• Adult = 1.0 to 7.5 U /L
• Newborn = 4 X adult level
  • Values are double in early childhood and then slowly fall to a normal level by the 18 to 20 years of age.
• Children  10 to 24 months = 3.4  to  11.8 U/L
  • child 25 months to 16 years = 1.2 to  8.8 U/L
• Another source
  • Adult = 22 to 59 mU/L at 37  °C
  • Child = Approximately 2 times the adult value.
  • Newborn = Approximately 4 times the adult value.
• Another source
  • Adult/elderly = 3.0 to 8.2 U/dL (22 to 59 mU at 37 °C).
    • Levels are slightly higher in men than women due to increased muscle mass.
  • Newborn = 2 to 4 times the adult level.
  • Child = Approximately twice the adult result.

The Aldolase level is increased in:

1. Cell destruction like Acute myocardial infarction (5 to 8 times of the normal).
2. Burns.
3. Acute Hepatitis (Viral or toxic). It is raised in the early stage of viral or toxic hepatitis.
4. Inflammatory diseases of muscles (Myopathy).
5. Raised in skeletal muscle disease or injury.
6. Raised in Muscular dystrophy. It is raised in pseudo hypertrophic muscular dystrophy (as the CPK is also raised).
   1. Duchenne’s muscular dystrophy.
   2. Trauma involving the muscles.
7. Carcinoma of the prostate (about 6 times the normal).
8. Cancer involving the lung, breast, liver, GIT, or genitourinary system.
9. Myelocytic leukemia (about 6 times the normal).
10. Megaloblastic and hemolytic anemia (about 10 to 13 times the normal).
11. In neoplastic diseases like carcinomatous metastasis to liver, lung, breast, genitourinary system, melanoma, and CNS tumors.
12. This may be raised in eosinophilia-myalgia syndrome.
13. Trichinosis.
14. Hemolytic anemia.
15. Gangrene.
16. Melanoma.

It is Normal in:

1. Neurogenic muscle atrophy.
2. Cirrhosis (or maybe slightly increased).
3. Obstructive jaundice (or maybe slightly increased).

Decreased Aldolase level is seen in:

1. Hereditary fructose intolerance.
2. This may indicate late muscular dystrophy.

• This test is nonspecific, so not commonly requested except for follow-up on muscle diseases.
• This is also not recommended due to the CPK raised level in all these conditions where aldolase is raised.

Importance

• The increase in the level reflects the intensity of the disease, and one can serially measure to know the effect of treatment by corticosteroids.
• CK is considered the choice of test for muscular diseases.

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