Reasons, Procedure & Preparation For Alkaline Phosphatase Isoenzymes

Submitted on March 27, 2012

Phosphatase is an enzyme that is primarily made in the liver and bone while other organs such as the kidneys and intestines also contribute to its production to a smaller degree. The enzyme is also created by the placenta of pregnant women usually in their third trimester. While normal values of alkaline phosphatase may vary from lab to lab, the generally accepted levels read at between 30 and 126 nits per liter of blood in adults and between 30 to 300 units per liter in children. Children would usually have higher levels of alkaline phosphatase than adults because of continuing bone growth.

Alkaline Phosphatase Isoenzymes Tests

Alkaline phosphatase comes in many different forms, depending largely on the area of the body and organ in which they are produced. Alkaline phosphatase isoenzyme tests will help measure the amounts of different types of alkaline phosphatase present in the blood. This test is also regularly ordered if the doctor is unaware of the exact reason for an increase in the ALP levels of the body. Any evidence of liver disease along with high ALP levels will be the sign of blocked bile ducts. Very often, one will also see that individuals affected by cancer that has spread to the liver or bones will have higher levels of ALP and these tests can help doctors identify if this has happened.

Reasons Why It is Conducted

Isoenzymes of alkaline phosphatase tests are performed to help diagnose conditions such as liver disease, parathyroid disease, vitamin D deficiency, bone disease and upper abdominal pain. It is also usually administered to identify the amount of damage being caused to your liver by consuming certain medications.

A high reading of ALP levels could be an indicator for a number of conditions such as rickets, leukemia, bone disease, hepatitis, anemia, thyroid gland inflammation and hepatitis amongst a host of others. Low levels may be an indicator of protein deficiency, poor nutrition, too much vitamin D or too little Vitamin C.


Since the test is usually performed with a routine blood test, there is usually no special preparation required. However, you may be instructed to avoid eating anything for about 10 to 12 hours prior to the isoenzyme of alkaline phosphatase test as the ALP levels tend to be higher after eating. Also inform your doctor about any medication you are taking, prescription or non prescription as they do tend to affect the readings of your test.


Like most blood test, isoenzymes of alkaline phosphatase tests will require a sample of blood to be drawn from the back of the elbow with the help of a syringe.