ALP isoenzyme test Health Article

Why the test is performed

This test may be used to diagnose:

• Liver disease
• Biliary disease (jaundice)
• Parathyroid disease
• Vitamin D deficiency
• Upper abdominal pain
• Bone disease

It may also be done to check liver function and to see how medicines you take may affect your liver.

Normal Values

The normal value is 20 to 140 IU/L (international units per liter). Normal value ranges may vary slightly among different laboratories. Talk to your doctor about the meaning of your specific test results.

Adults have lower levels of ALP than children. Bones that are still growing produce higher levels of ALP. During some growth spurts, levels can be as high as 500 IU/L. For this reason, the test is usually not done in children, and abnormal results refer to adults.

The isoenzyme test results can reveal whether the increase is in "bone" ALP or "liver" ALP.

What abnormal results mean

Higher-than-normal ALP levels may indicate:

• Pregnancy
• Healing bone fracture
• Liver diseases
• Biliary obstruction
• Hepatitis
• Bone disease
• Paget's disease
• Osteoblastic bone tumors
• Osteomalacia
• Rickets
• Skeletal disease
• Anemia
• Rickets
• Leukemia
• Thyroid gland inflammation
• Hyperparathyroidism
• Chronic alcohol ingestion

Lower-than-normal levels of ALP may indicate:

• Protein deficiency
• Magnesium deficiency
• Too much vitamin D or too little vitamin C
• Poor nutrition

What the risks are

Veins and arteries vary in size from one patient to another and from one side of the body to the other. Obtaining a blood sample from some people may be more difficult than from others.

Other risks may include:

• Excessive bleeding
• Fainting or feeling light-headed
• Hematoma (blood accumulating under the skin)
• Infection (a slight risk any time the skin is broken)

Special considerations

This test is about 80% accurate for identifying the specific locations of cancers or disease. However, it is not a reliable screening test because levels may be high for unknown reasons and return to normal. Unless there are signs of a disease, slightly higher-than-normal values of ALP in the CHEM-20 test are not considered significant.