ALP blood test
Alkaline phosphatase
In short
A typical adult ALP result is 35 to 104 U/L for women and 40 to 129 U/L for men. A mild rise is common and often has a simple cause. If GGT is also high, the liver is the likely source; if GGT is in range, bone is more likely. Always read your result against the range printed on your own report.
An enzyme from the liver and bile ducts, and from bone.
ALP comes mainly from the liver and its bile ducts, which drain digestive juice, and from bone. It rises when bile flow slows or when bone is growing or rebuilding. That is why it runs higher in growing teenagers and in pregnancy, when the placenta makes it too.
Is my ALP high or low?
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Typical range
| For | Range | Unit |
|---|---|---|
| Female | 35–104 | U/L |
| Male | 40–129 | U/L |
Typical ranges for adults. Labs differ a little, so the range printed next to your result is the one to go by.
If your ALP is high
A mild rise is common and often has a simple cause. If GGT is also high, the liver is the likely source; if GGT is in range, bone is more likely.
Common reasons
- Bone growth in teenagers, or a healing broken bone
- Pregnancy, especially the last months, when the placenta makes ALP
- Low vitamin D, which can make bone release more ALP
- Extra fat stored in the liver
- Some medicines, including some seizure medicines and some antibiotics
- Less often: an overactive parathyroid gland (it controls calcium) or a bone disorder
- Less often: a blocked bile duct, liver scarring, or cancer in liver or bone
If your ALP is low
A low ALP is uncommon. It often has a simple cause, such as hormone medicines or low zinc.
Common reasons
- Birth control pills or hormone therapy
- Low zinc, or too little protein in the diet
- An underactive thyroid
- Less often: a rare inherited condition that weakens bones and teeth (hypophosphatasia)
What can throw it off
Pregnancy, a healing fracture and bone growth in teenagers all raise ALP.
Questions to take to your appointment
- 1Does my GGT point to my liver or my bones?
- 2Could pregnancy, a recent fracture or a medicine explain this?
- 3Should my vitamin D and calcium be checked?
Read together with
Doctors rarely read ALP alone. These usually sit next to it.
- GGTA liver enzyme that rises with alcohol and bile duct problems.
- ALTAn enzyme that lives mostly inside liver cells.
- Total bilirubinA yellow pigment made when old red blood cells break down.
- CalciumA mineral that builds bones and keeps nerves and muscles working.
- Vitamin DThe main blood test of the body's vitamin D supply.
Quick answers
What is the ALP blood test?
ALP (Alkaline phosphatase): An enzyme from the liver and bile ducts, and from bone. ALP comes mainly from the liver and its bile ducts, which drain digestive juice, and from bone. It rises when bile flow slows or when bone is growing or rebuilding. That is why it runs higher in growing teenagers and in pregnancy, when the placenta makes it too.
What is a normal ALP level?
For most adults, ALP is typically 35 to 104 U/L for women and 40 to 129 U/L for men. Labs differ a little, so the range printed next to your result is the one to go by.
What does a high ALP mean?
A mild rise is common and often has a simple cause. If GGT is also high, the liver is the likely source; if GGT is in range, bone is more likely. Common reasons include bone growth in teenagers, or a healing broken bone; pregnancy, especially the last months, when the placenta makes ALP; low vitamin D, which can make bone release more ALP; and extra fat stored in the liver. A doctor reads it together with your other results and how you feel.
What does a low ALP mean?
A low ALP is uncommon. It often has a simple cause, such as hormone medicines or low zinc. Common reasons include birth control pills or hormone therapy; low zinc, or too little protein in the diet; an underactive thyroid; and less often: a rare inherited condition that weakens bones and teeth (hypophosphatasia).
What can affect my ALP result?
Pregnancy, a healing fracture and bone growth in teenagers all raise ALP.
What should I ask my doctor about my ALP?
Questions worth taking to the appointment: Does my GGT point to my liver or my bones? Could pregnancy, a recent fracture or a medicine explain this? Should my vitamin D and calcium be checked?
What this page can’t do
It reads each number on its own.
Doctors read results together — ALT with AST, ferritin with hemoglobin, TSH with free T4. A pattern says more than any single flag.
It doesn't know you.
Your age, your medicines, how you feel and your last result all change what a number means.
It doesn't remember.
Close this page and your results are gone. That's on purpose: nothing was ever sent to us.
We also make Vita: Health Coach, an app for those parts. It reads your whole report with your medicines and history in mind, answers follow-up questions in plain words, and keeps your reports in one place — for you and for the people you look after.
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