Serum Alkaline Phosphatase Lab Test

This test measures the level of the enzyme alkaline phosphatase in blood.

Since the ALP enzyme is synthesized mainly in the liver and the bone, its presence in higher amounts in blood, reflect disorders of liver or bone.

Preparing for the Alk Phos Test

  • Food, especially fatty food, may temporarily elevate ALP levels in the blood. So, one is required not to take any food since 8 hours prior to this test.
  • Also, inform your doctor about any medicines you are taking, as some medicines may interfere with the readings of the Serum Alk Phos test. These include medications for diabetes, birth control pills, aspirin when taken for a long period etc.

Normal Range of Values

Adults: 25-100 units per liter (U/L)
Children:  Less than 350 U/L

Children have higher alk phos values as their bones are more active in phases of growth. Also, women in pregnancy may show higher ALP values. This is because the placenta also produces some amount of this enzyme.

Conditions Showing High ALP Levels

Elevated alkaline phosphatase levels are seen in various diseases such as:

  • Hepatitis
  • Obstructive jaundice
  • Liver cancers
  • Cirrhosis
  • Gall bladder stones
  • Osteomalacia or rickets
  • Bone tumor or metastatic conditions
  • Overactive parathyroid gland
  • Vitamin D deficiency
  • After a bone fracture in the healing phase, where the bone activity is increased.

Conditions Showing Low Levels

This occurs commonly in either nutritional deficiency states or conditions of malabsorption.

When alk phos levels are high, further investigations are carried out to rule out any liver or bone problem.

Your doctor may look for jaundice or order LFT to assess liver functioning.

Bone density may be assessed by various tests and scans.

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