Definition
What Alkaline Phosphatase measures
Alkaline phosphatase is an enzyme made mainly in the bile ducts of the liver and in bone. A blood level reflects contributions from both sources.
Illustrative sample band · Synthetic
68U/L
34Sample target 40–100 U/L127
Why it matters
How clinicians usually read it
It flags a different liver pathway than ALT and AST — bile flow — and separately reflects bone turnover, so an elevation is a routing question: liver or bone?
When it reads low
A lower value can mean
A low ALP is uncommon and can accompany certain nutrient deficiencies or rare inherited conditions. It is usually reviewed with the clinical picture rather than acted on alone.
When it reads high
A higher value can mean
A higher ALP can come from bile-duct irritation, certain medications, bone growth or healing, or vitamin D-related bone turnover. Follow-up tests can identify the source.
Questions for a clinician
Bring the number into a real conversation
01
If this ALP is elevated, how do we tell liver from bone?
02
Do my other liver enzymes and bilirubin support a bile-flow story?
03
Is a recent fracture, growth phase, or bone condition relevant here?
Educational boundary
Educational information only. Displayed ranges are illustrative sample bands, not a diagnosis, treatment plan, or substitute for the contracted laboratory report and a qualified clinician.
See it as a sample result
The sample dashboard shows an illustrative reading, target band, and trend for Alkaline Phosphatase.