Alkaline Phosphatase

Measured in U/L

An enzyme found in both liver and bone, so an elevated result doesn't point to one source without other markers.

What it is

Alkaline phosphatase (ALP) is an enzyme — a protein that speeds up chemical reactions — found mainly in the liver's bile ducts and in bone, with smaller amounts elsewhere, including the placenta in pregnancy. Because it comes from more than one place, it's read alongside other liver markers like ALT, AST, and bilirubin, and sometimes with a companion test (such as GGT) to help suggest whether liver or bone is the likelier source. It also varies naturally by life stage: growing children and teens normally run much higher, and it can rise in pregnancy or while a fracture heals.

Typical range

  • Male40–129 U/L
  • Female35–104 U/L

Source · Mayo Clinic Laboratories (ALP) (2026)

Reference ranges vary between laboratories, and what is normal for you depends on your own history. Your own lab’s range is the one printed on your report.

Worth asking your clinician

  • Given my age and situation, is my alkaline phosphatase in an expected range?
  • Would another marker like GGT help clarify whether this is coming from liver or bone?
  • Is this a value you'd want to recheck over time to see whether it's stable?