Alkaline Phosphatase (ALP / ALKP)

Clinical definition of the Alkaline Phosphatase test
Alkaline phosphatase (ALP) is a hydrolase enzyme responsible for dephosphorylation from molecules such as nucleotides, proteins, and alkaloids. It is found in several tissues throughout the body, including liver, bone, bile duct, kidney, bowel (intestine), and in the placenta of women who are pregnant.

Why is the Alkaline Phosphatase test done?
To diagnose, screen or monitor treatment for liver or bone disorder. In case of a liver disease, one or more bile ducts may be blocked which causes high amounts of ALP to be released into the blood by damaged liver cells. Similarly, any activity of bone cells affecting the growth of bones would cause an increase in the ALP levels. Pregnant women, growing children and people with healing fractures may also show a temporary increase in ALP levels.

What are the common signs/symptoms when the Alkaline Phosphatase test is done?
Liver disease:

  • Nausea
  • Vomiting
  • Abdominal swelling and/or pain
  • Jaundice
  • Dark urine, light colored stool
  • Weakness
  • Fatigue
  • Anorexia
  • Itching sensation

Bone disease:

  • Distorted bones
  • Bone and/or joint pain
  • Increased frequency of fractures

Who should do the Alkaline Phosphatase test (Target population)?
Liver disease:

  • Obese people
  • People who drink  heavily
  • Those exposed to hepatitis viruses or liver toxins & may have metabolic syndrome or insulin resistance
  • People with an inherited disorder affecting the liver such as Wilson's disease or hemachromatosis

Bone disease:

  • People suffering from Paget's disease
  • Those having bone related disorders like vitamin D deficiency.

What should I do before the Alkaline Phosphatase test?

Specimen type

Specimen collection procedure

Preparatory instructions during specimen collection*


(Blood Sample)


(Collection of blood from a vein, usually from the arm)

Fasting Required.

Fasting samples have to be collected after a minimum 8-hour overnight fasting status.

Clear fluids like water is allowed during this period. Refrain from consumption of early morning beverages like tea, coffee and milk until specimen collection is completed.

In case of diabetics on oral or injectable hypoglycemic agents, consult your physician about continuing with these medications prior to specimen collection.

*Subjects suffering from any illness or on oral or injectable medications are advised to consult their physician prior to requesting any tests or procedures.

How do I interpret my Alkaline Phosphatase test results?



20 to 140 IU/L


>140 IU/L

Liver / Bone Disorder

Inference: High ALP usually means that either the liver has been damaged or a condition causing increased bone cell activity is present. If it is not clear from signs and symptoms or from other routine tests whether the high ALP is due to liver or bone, then a test for ALP isoenzymes may be necessary to distinguish between bone and liver ALP.
‘*A Reference range is a set of values which helps the healthcare professional to interpret a medical test. It may vary with age, gender, and other factors. Reference ranges may also vary between labs, in value & units depending on instruments used and method of establishment of reference ranges’

Diseases/conditions related to the Alkaline Phosphatase test

  • Liver cancer
  • Cirrhosis
  • Hepatitis
  • Paget's disease
  • Rheumatoid arthritis 

Other tests related to the Alkaline Phosphatase test

  • SGOT
  • SGPT
  • GGTP
  • Bilirubin- Direct
  • Bilirubin-Total
  • Liver Function Test
  • Bone markers

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Alkaline Phosphatase (Serum)