High levels of alkaline phosphatase (ALP) in the blood may indicate liver disease or certain bone disorders. However, an ALP test alone cannot diagnose a condition, and additional tests may be needed to determine the underlying cause of high ALP levels. Some possible causes of high ALP levels include:

• Liver disease, such as cirrhosis, hepatitis, or liver cancer
• Bone disorders, such as Paget disease, bone fractures, or bone cancer
• Bacterial infections, such as sepsis or osteomyelitis
• Blockage in the bile ducts
• Certain medications
• Pregnancy

It is important to note that normal ALP levels vary with age and sex, and ALP levels are typically elevated during childhood and puberty due to bone growth and development. ALP levels are also higher in males than females between the ages of 15 to 50 years, and then rise again in old age. ALP levels may also be higher in pregnant people and in people who are healing from a bone fracture.

Low levels of ALP are less common and may be a sign of a lack of zinc, malnutrition, pernicious anemia, thyroid disease, Wilson disease, or hypophosphatasia, a rare genetic disease that affects bones and teeth.