What causes high alkaline phosphatase levels in the blood

Q: How serious is elevated alkaline phosphatase?

Its important to note that elevated levels of ALP can range in severity. While a very high ALP level often means you have liver damage or a bone disorder, mildly elevated levels can be caused by many different factors — not necessarily a medical condition that needs treatment.

Does this test have other names?

ALP

What is this test?

The alkaline phosphatase (ALP) test measures how much alkaline phosphatase you have in your blood. Alkaline phosphatase is an enzyme found throughout your body. But it is mainly in your liver, bone, kidney, and digestive tract.

Why do I need this test?

You may need this test if you're at risk for a condition that affects your liver. For instance, your blood can show higher levels of ALP if one of the bile ducts that drains your liver becomes blocked. Conditions such as liver cancer, cirrhosis, and hepatitis can also cause ALP levels to rise. Bone disorders like Paget disease and healing fractures are other things that may affect your ALP levels. Younger children with high bone growth may also have higher ALP levels.

What other tests might I have along with this test?

The ALP test may be done as part of a routine liver panel, a group of blood tests that looks at how well your liver is working.

If your ALP levels are too high, your healthcare provider may order an ALP isoenzyme test to find out what type of ALP is elevated in your blood. Liver disorders make different forms of ALP than bone disorders.

What do my test results mean?

Test results may vary depending on your age, gender, health history, and other things. Your test results may be different depending on the lab used. They may not mean you have a problem. Ask your healthcare provider what your test results mean for you.

ALP results are reported in units per liter (U/L). For men and women older than age 18, an ALP level between 44 and 147 U/L is considered normal. The normal range for children is higher than that for adults, especially for infants and teens because their bones are growing rapidly.

How is this test done?

The test is done with a blood sample. A needle is used to draw blood from a vein in your arm or hand.

Does this test pose any risks?

Having a blood test with a needle carries some risks. These include bleeding, infection, bruising, and feeling lightheaded. When the needle pricks your arm or hand, you may feel a slight sting or pain. Afterward, the site may be sore.

What might affect my test results?

Eating before the test may slightly increase your ALP levels for a few hours.

Pregnancy may cause higher levels of ALP. Teens, who often grow rapidly, tend to have higher ALP levels than people in other age groups.

How do I get ready for this test?

You may need to fast—not eat or drink anything—for several hours before this test. You may be asked to stop taking any blood-thinning medicines before the test.

Be sure your healthcare provider knows about all medicines, herbs, vitamins, and supplements you are taking. This includes medicines that don't need a prescription and any illegal drugs you may use.

Alkaline phosphatase

Alkaline phosphatase (ALP) is a protein found in all body tissues. Tissues with higher amounts of ALP include the liver, bile ducts, and bone.

A blood test can be done to measure the level of ALP.

A related test is the ALP isoenzyme test.

How the Test is Performed

A blood sample is needed. Most of the time, blood is drawn from a vein located on the inside of the elbow or the back of the hand.

How to Prepare for the Test

You should not eat or drink anything for 6 hours before the test, unless your health care provider tells you otherwise.

Many medicines can interfere with blood test results.

Your provider will tell you if you need to stop taking any medicines before you have this test.
DO NOT stop or change your medicines without talking to your provider first.

How the Test will Feel

You may feel slight pain or a sting when the needle is inserted. You may also feel some throbbing at the site after the blood is drawn.

Why the Test is Performed

This test may be done:

To diagnose liver or bone disease
To check if treatments for those diseases are working
To check for side effects from medicines

Normal Results

The normal range is 44 to 147 international units per liter (IU/L) or 0.73 to 2.45 microkatal per liter (µkat/L).

Normal values may vary slightly from laboratory to laboratory. They also can vary with age and sex. High levels of ALP are normally seen in children undergoing growth spurts and in pregnant women.

The examples above show the common measurements for results for these tests. Some laboratories use different measurements or may test different specimens.

What Abnormal Results Mean

Abnormal results may be due to the following conditions:

Higher-than-normal ALP levels

Biliary obstruction
Bone disease
Eating a fatty meal if you have blood type O or B
Healing fracture
Hepatitis
Hyperparathyroidism
Hyperthyroidism
Leukemia
Liver disease
Lymphoma
Osteoblastic bone tumors
Osteomalacia
Paget disease of bone
Sarcoidosis

Lower-than-normal ALP levels

Hypophosphatasia
Hypothyroidism
Malnutrition
Pernicious anemia
Protein deficiency
Wilson disease
Zinc deficiency

Other conditions for which the test may be done:

Alcoholic liver disease (hepatitis/cirrhosis)
Alcoholism
Biliary stricture
Gallstones
Giant cell (temporal, cranial) arteritis
Multiple endocrine neoplasia (MEN) II
Pancreatitis
Renal cell carcinoma

References

Fogel EL, Sherman S. Diseases of the gallbladder and bile ducts. In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine. 26th ed. Philadelphia, PA: Elsevier; 2020:chap 146.

Korenblat KM, Berk PD. Approach to the patient with jaundice or abnormal liver tests. In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine. 26th ed. Philadelphia, PA: Elsevier; 2020:chap 138.

Martin P. Approach to the patient with liver disease. In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine. 26th ed. Philadelphia, PA: Elsevier; 2020:chap 137.

Pincus MR, Abraham NZ, Bluth M. Interpreting laboratory results. In: McPherson RA, Pincus MR, eds. Henry's Clinical Diagnosis and Management by Laboratory Methods. 24th ed. Philadelphia, PA: Elsevier; 2022:chap 9.

Version Info

Last reviewed on: 5/1/2021

Reviewed by: David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.

How serious is elevated alkaline phosphatase?

It's important to note that elevated levels of ALP can range in severity. While a very high ALP level often means you have liver damage or a bone disorder, mildly elevated levels can be caused by many different factors — not necessarily a medical condition that needs treatment.

What is the treatment for high alkaline phosphatase?

Some good options include milk thistle, NAC, taurine, B vitamins, and vitamin C. Additionally, get enough sun, exercise, omega-3 fatty acids, and coffee. Reduce alcohol and stop smoking — they both lower alkaline phosphatase levels and support good health.

What infections cause high alkaline phosphatase?

Extremely high elevations of alkaline phosphatase are most frequently seen in patients with sepsis, malignant obstruction, and AIDS. Patients with sepsis can have an extremely high alkaline phosphatase level and a normal bilirubin.