What Does High Alkaline Phosphatase Mean on Blood Tests?

Blood tests are used to assess general health, and also help diagnosis underlying medical conditions. Levels of alkaline phosphatase -- an enzyme in the blood -- can be elevated by liver disease, or less serious conditions including pregnancy and over-the-counter drug use. See your doctor to discuss any concerns you may have after a blood test.

A doctor is taking a blood sample from a patient. (Image: Purestock/Purestock/Getty Images)


Alkaline phosphatase -- often refers to as "ALP" or "Alk Phos" on lab sheets -- is an isoenzyme. Isoenzymes are groups of slightly different enzymes that work together to perform the same function. Although alkaline phosphatase found in the bile ducts is slightly different from alkaline phosphatase found in bone, both types remove phosphate groups from many different molecules.

Drug Usage

Many common over-the-counter and prescription drugs can elevate alkaline phosphatase levels. For example, hypertension drugs such as propanolol or verapamil or gout treatments such as allopurinol can raise levels. Antibiotics such as erythomycin and ulcer treatments such as ranitidine are also common culprits.

Liver Diseases

High alkaline phosphatase levels can be associated with various liver diseases such as as hepatic cancer, cirrhosis, fatty liver and hepatitis. Doctors will usually run a liver panel blood test-- also called a hepatic function test. By looking at a variety of liver enzymes, doctors can assess liver function.

Bone Growth

Alkaline phosphatase is also evidence of bone growth, which is why this enzyme is elevated in both pregnant women and children. For example, while normal adult levels range from 30 to 120 UL, levels in children can be as high as 500 UL. In addition to this healthy growth, high alkaline phosphatase levels can be symptomatic of uncontrolled bone growth occurring in bone cancers and other diseases.

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