Alkaline Phosphatase (ALP)

What is Alkaline Phosphatase?

Alkaline phosphatase (ALP) is an enzyme found primarily in the liver, bones, and bile ducts. It helps break down proteins and is released when these tissues are damaged or during periods of high metabolic activity like bone growth.

Why is it Tested?

Doctors order ALP to evaluate liver function, investigate bone disorders, assess bile duct obstruction, and monitor certain medications’ effects. It’s included in comprehensive metabolic panels and helps distinguish between liver and bone diseases.

Normal Ranges

Reference ranges for alkaline phosphatase:

Adults: 44–147 U/L

Levels may be higher in children and adolescents due to bone growth, and can vary between different laboratory methods.

Reference ranges vary by authority. Track yours across multiple standards with automatic unit conversions in LabsVault.

What do Abnormal Results Mean?

Abnormal results are not a diagnosis. Always discuss your results with a qualified healthcare provider before making any medical decisions.

Low Alkaline Phosphatase

Reduced levels may indicate:

Malnutrition
Zinc deficiency
Hypothyroidism
Certain genetic conditions
Some medications

High Alkaline Phosphatase

Elevated levels suggest:

Liver disease or bile duct obstruction
Bone disorders (Paget’s disease, fractures)
Certain cancers
Pregnancy (third trimester)
Growing children/adolescents
Some medications

How to Track Over Time

ALP levels help monitor liver disease progression and treatment response. When elevated, tracking alongside other liver enzymes helps determine whether the source is hepatic or skeletal. Persistent elevations warrant further investigation to identify the underlying cause.

Alkaline Phosphatase