Healthcare professionals may measure ALP levels in international units per liter (IU/l). The reference range for normal levels of ALP can vary from laboratory to laboratory. The United Kingdom’s National Health Service (NHS) lists the reference range for adults aged 18 years and older as 30–130 IU/l.
However, other labs may consider the normal range to be different, and research suggests that normal upper limits of ALP levels may vary depending on multiple factors, such as a person’s age, sex assigned at birth, and ethnicity.
A person should check the reference report that comes with their test results to fully understand the findings. They may also wish to discuss the results with their doctor for further guidance.