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Normal alkaline phosphatase (ALP) level in the blood

Blood test
Normal alkaline phosphatase (ALP) level in the blood
Last update: 03/04/2020

What is the normal alkaline phosphatase (ALP) level in the blood?

Adults30 - 120 U/l17 - 120 U/l
16 to 18 years old52 - 171 U/l47 - 119 U/l
13 to 15 years old74 - 390 U/l50 - 162 U/l
10 to 12 years old42 - 362 U/l51 - 332 U/l
7 to 9 years old86 - 315 U/l69 - 325 U/l
4 to 6 years old93 - 309 U/l96 - 297 U/l
1 to 3 years old104 - 345 U/l108 - 317 U/l
1 month to 1 year old82 - 383 U/l124 - 341 U/l
0 to 1 month old75 - 316 U/l48 - 406 U/l

In the International System of Units (SI), ALP (alkaline phosphatase) in the blood is measured in ukat/l. The normal ALP (alkaline phosphatase) levels in the blood in the SI are:

Adults0.5 - 2 ukat/l0.28 - 2 ukat/l
16 to 18 years old0.87 - 2.85 ukat/l0.78 - 1.98 ukat/l
13 to 15 years old1.23 - 6.5 ukat/l0.83 - 2.7 ukat/l
10 to 12 years old0.7 - 6 ukat/l0.85 - 5.53 ukat/l
7 to 9 years old1.43 - 5.25 ukat/l1.15 - 5.41 ukat/l
4 to 6 years old1.55 - 5.15 ukat/l1.6 - 4.95 ukat/l
1 to 3 years old1.73 - 5.75 ukat/l1.8 - 5.28 ukat/l
1 month to 1 year old1.37 - 6.38 ukat/l2.06 - 5.68 ukat/l
0 to 1 month old1.25 - 5.27 ukat/l0.8 - 6.77 ukat/l

Why normal levels can differ across different labs?

Each laboratory must establish its own normal ranges for the ALP (alkaline phosphatase) in the blood. These ranges depend on the makeup of the local population, the technologies used and the accuracy of the measurement. There may be also slight differences in the normal levels, according to age, gender, race or ethnic origin, geographic region, diet, type of sample and other relevant status.

Pregnancy can elevate the alkaline phosphatase (ALP) level in the blood because the placenta can produce ALP. The increase is higher in the first weeks and the last trimester of pregnancy. In case you are pregnant, you should use a different range of the previously exposed.

What is the role of alkaline phosphatase (ALP)?

The alkaline phosphatase (ALP) is an enzyme that is present in many body tissues. It is present in the liver, bile ducts, bones, intestine and placenta.

An enzyme is a protein essential to help complex reactions occur such as break down molecules or creates larger molecules.

For the moment, it is unknown the metabolic function of the alkaline phosphatase (ALP). Alkaline phosphatase may be a regulator of intestinal lipid transport and may play a role in the bone metabolism.

Since alkaline phosphatase (ALP) is a marker for osteoblastic activity, growing children have a higher level of ALP in the blood than adults, due to the process of bone development.

What is the alkaline phosphatase (ALP) blood test used for?

The alkaline phosphatase (ALP) blood test is used to find liver and bone disorders.

The alkaline phosphatase (ALP) level gives more information when it is studied along with the GGT (Gamma-glutamyltransferase) blood test:

  • If the alkaline phosphatase (ALP) is high and the GGT is in normal range it suggests a bone disorder.
  • If the alkaline phosphatase (ALP) is high and the GGT is also high it suggests a liver disease such as cirrhosis, liver cancer or bile duct obstruction.

A low level of alkaline phosphatase (ALP) in the blood may be due to:

  • Zinc deficiency (the most common situation)
  • Adrenal gland disorder
  • Low-protein diet or malnutrition

Where can I find more information about alkaline phosphatase (ALP) level in the blood?

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Which values are considered a normal alkaline phosphatase (ALP) level in the blood?

The following values are considered to be normal values:

IMPORTANT: These levels are expressed in U/L. They are an example of a healthy man of about 45 years old with no known disease and not taking any medication. The ranges can be different depending on the laboratory or on your personal circumstances.

Normal ranges of alkaline phosphatase (ALP) in the blood in children and in pregnancy are very different at the values presented here. In that case you must use the respective reference tables.

Alkaline phosphatase
30 U/L31 U/L32 U/L33 U/L34 U/L35 U/L36 U/L37 U/L
38 U/L39 U/L40 U/L41 U/L42 U/L43 U/L44 U/L45 U/L
46 U/L47 U/L48 U/L49 U/L50 U/L51 U/L52 U/L53 U/L
54 U/L55 U/L56 U/L57 U/L58 U/L59 U/L60 U/L61 U/L
62 U/L63 U/L64 U/L65 U/L66 U/L67 U/L68 U/L69 U/L
70 U/L71 U/L72 U/L73 U/L74 U/L75 U/L76 U/L77 U/L
78 U/L79 U/L80 U/L81 U/L82 U/L83 U/L84 U/L85 U/L
86 U/L87 U/L88 U/L89 U/L90 U/L91 U/L92 U/L93 U/L
94 U/L95 U/L96 U/L97 U/L98 U/L99 U/L100 U/L101 U/L
102 U/L103 U/L104 U/L105 U/L106 U/L107 U/L108 U/L109 U/L
110 U/L111 U/L112 U/L113 U/L114 U/L115 U/L116 U/L117 U/L
118 U/L119 U/L120 U/L     
Medically reviewed by Javier Muga Bustamante Ph.D. on 03/04/2020


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  • Moss DW, Henderson RA. Clinical Enzymology. In: Burtis CA, Ashwood ER, eds. Tietz textbook of clinical chemistry. Philadelphia:WB Saunders Company, 1999; 676-684. ISBN 9780721656106.
  • Tietz NW, Rinker D, Shaw LM. IFCC methods for the measurement of catalytic concentration of enzymes Part 5. IFCC method for alkaline phosphatase. J Clin Chem Clin Biochem 1983;21:731-48.
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  • Severity grading in drug induced liver injury. U.S. National Library of Medicine. Available on:

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