ALKALINE PHOSPHATASE TEST

What is the purpose of this test: The alkaline phosphatase test is used to help detect hepatobiliary and bone disorders.
How to prepare:
  • A simple blood sample is taken.
  • Overnight fasting is usually required.
Target values:
  • Women: 35 to 104 U/L
  • Men: 40 to 129 U/L

Children/adolescents and women who are pregnant have higher levels of alkaline phosphatase due to bone growth in children and placental growth in women during pregnancy.
Associated tests: A liver function test, a gamma-glumatyl-transpeptidase test and a 5′-nucleotidase test can help confirm hepatobiliary disorder.

 

General Information

Alkaline phosphatase is an enzyme found in the intestines, spleen, kidneys and placenta. It is the alkaline phosphatase enzymes in the liver and bones however, that are responsible for serum alkaline phosphatase activity.

What does an abnormal test result mean?

If test results are high

  • High alkaline phosphatase levels may be indicative of disease in the liver (cholestasis, neoplasia, hepatitis, cirrhosis, etc.) or bone (fracture, tumour, Paget’s disease, etc.).

If test results are low

  • Abnormally low alkaline phosphatase levels may be the result of: Wilson’s disease, hypothyroidism, pernicious anemia, zinc deficiency or hypophosphatasia.

 

Factors that can affect results

Upwards

 

  • Food
  • Race (higher incidence in African Americans)
  • High body mass index
  • Smoking

 

Downwards

 

  • Hemolysis

Some drugs may affect levels of alkaline phosphatase in the blood. A few examples are listed below:

  • Acetylsalicylic acid (Aspirin®)
  • Alendronate (Fosamax®)
  • Aminoglycosides
  • Amiodarone (Cordarone®)
  • Anticonvulsants
  • Chlorpromazine (Largactil®)
  • Clofibrate (Atromide ®)
  • Erythromycin (Eryc®)
  • Esterified estrogens
  • Isoniazid (Isotamine®)
  • Levothyroxine (Synthroid®)
  • Lithium (Carbolith®)
  • Methyltestosterone (Metandren®)
  • Oral contraceptives
  • Oral hypoglycaemic drugs
  • Phenothiazine
  • Theophylline (Theo Dur®)

 

What you should know before going for this test

Before going for a blood test, examination or other, it is always a good idea for you to have a complete list of all prescription and over the counter medications and/or natural products you may be taking. If you are unsure or have any questions, your pharmacist will be able provide you with additional information.