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Liver

Alkaline phosphatase (ALP): what the value says about the liver, bile ducts and bones

According to the Cleveland Clinic, an enzyme is a protein in a cell that allows certain bodily processes to happen, and alkaline phosphatase is an enzyme found in many places: in the liver, the bile ducts, the bones, the kidneys, the intestines and, in pregnant women, the placenta. In the blood it comes mainly from the liver and the bones. According to the Cleveland Clinic, its exact function is not yet known, although researchers believe the enzyme is important for multiple processes.

According to the Cleveland Clinic, a high alkaline phosphatase may indicate liver disease or a bone disorder, and a low value, which is less common, may indicate malnutrition or a zinc or magnesium deficiency, among other things. According to the Cleveland Clinic, the test alone cannot diagnose a condition, and only a blood test shows how high the value is.

Star-SHL uses 45 to 128 U/l for men aged 19 to 50 inclusive and 38 to 123 U/l for women of that age. Certe uses less than 115 U/l in men and less than 98 U/l in women above 19, and Diagnostiek voor U 40 to 120 U/l above 18.

Doctor's Assessment Included

Alkaline phosphatase is an enzyme that in the blood comes mainly from the liver and the bones. According to the Cleveland Clinic, a high value may indicate liver disease or a bone disorder, a low value malnutrition, among other things.

  • For alkaline phosphatase, Star-SHL and Unilabs use 45 to 128 U/l for men aged 19 to 50 inclusive and 38 to 123 U/l for women of that age.
  • For alkaline phosphatase, Certe uses less than 115 U/l in men and less than 98 U/l in women above 19; Diagnostiek voor U 40 to 120 U/l above 18.
  • According to the Cleveland Clinic, an isoenzyme test can show whether alkaline phosphatase comes from the liver or the bones.

Reference Ranges

See the value that applies to you:

Choose male or female — this range differs by sex.

Enter your age — this range changes with age.

This range also depends on context such as cycle phase or sample material; the highlighted rows apply to your group.

Your reference range
u/l
38 209 u/l
Reference ranges by group, in u/l
Male · 13–18 years 63–190 u/l
63 190
Male · 19–50 years 45–128 u/l
45 128
Male · 51–65 years 46–126 u/l
46 126
Male · 66–80 years 44–134 u/l
44 134
Male · 81 years and older 45–145 u/l
45 145
Female · 6–12 years 107–209 u/l
107 209
Female · 13–18 years 44–149 u/l
44 149
Female · 19–50 years 38–123 u/l
38 123
Female · 51–65 years 48–142 u/l
48 142
Female · 66–80 years 47–138 u/l
47 138
Female · 81 years and older 45–146 u/l
45 146
38 209 u/l

Source: NVKC Reference population: Dutch general-practice population (NUMBER, n = 7,574,327)

Reference ranges may vary between laboratories. When you order a test, a BIG-registered doctor assesses your personal results in context. For treatment decisions, discuss your results with your GP.

Check your own value

ALP (Alkaline Phosphatase): what Dutch laboratories use

Reference ranges by group, in u/l
Star-shl · Male · 19–50 years 45–128 U/l
45 128
Star-shl · Female · 19–50 years 38–123 U/l
38 123
Star-shl · Male · 51–65 years 46–126 U/l
46 126
Star-shl · Female · 51–65 years 48–142 U/l
48 142
Star-shl · Male · 66–80 years 44–134 U/l
44 134
Star-shl · Female · 66–80 years 47–138 U/l
47 138
Star-shl · Male · 81 years and older 45–145 U/l
45 145
Star-shl · Female · 81 years and older 45–146 U/l
45 146
Unilabs · Female · 19–50 years 38–123 U/l
38 123
Unilabs · Female · 51–65 years 48–142 U/l
48 142
Unilabs · Female · 66–80 years 47–138 U/l
47 138
Unilabs · Female · 81 years and older 45–146 U/l
45 146
Unilabs · Male · 19–50 years 45–128 U/l
45 128
Unilabs · Male · 51–65 years 46–126 U/l
46 126
Unilabs · Male · 66–80 years 44–134 U/l
44 134
Unilabs · Male · 81 years and older 45–145 U/l
45 145
Certe · Female · 19 years and older · a limit, not a range < 98 U/L
98
Certe · Male · 19 years and older · a limit, not a range < 115 U/L
115
Diagnostiek voor U · Everyone · 19 years and older 40–120 U/L
40 120
0 160.6 u/l

Source: Star-shl

Source: Unilabs

Source: Certe

Source: Diagnostiek voor U

Each value as the laboratory itself publishes it, retrieved in 2026.

ALP (Alkaline Phosphatase): what this test measures

The alkaline phosphatase test measures how much of the enzyme is in the blood, in units per litre (U/l), without distinguishing where it comes from. According to the Cleveland Clinic, an isoenzyme test can tell which part of the body the enzyme originated in. Laboratories abbreviate the test as AF; Certe also lists ALP as a synonym.

ALP (Alkaline Phosphatase): why this value matters

Alkaline phosphatase matters because, according to the Cleveland Clinic, an abnormal value can reflect damage to tissue or disruption of normal bodily processes. According to the Cleveland Clinic, a very high value often means liver damage or a bone disorder. A mildly raised value can have many causes that do not always need treatment, and according to that source the provider will then likely monitor the value over time.

ALP (Alkaline Phosphatase): how the blood test works

Referral
No GP referral needed. After the order we arrange the referral through ZorgDomein, within one business day; orders after 17:00 or at the weekend start on the next business day. ZorgDomein emails a barcode, and that barcode is what the draw site needs.
The draw
A blood draw from a vein in the arm, at a partner laboratory's draw site. No home kit, no finger prick.
Which test
Liver checkup · €89,-
Where
650+ draw sites run by independent laboratories across the Netherlands. Draw sites

ALP (Alkaline Phosphatase): when is testing worthwhile?

According to the Cleveland Clinic, an alkaline phosphatase test may be ordered to help screen for, monitor or help diagnose liver and biliary diseases, bone disorders and other conditions. The test is usually part of a comprehensive metabolic panel or a liver panel, and according to the Cleveland Clinic, for such a comprehensive panel you will likely need to fast for 10 to 12 hours. According to the Cleveland Clinic, signs that can go with liver disease, such as jaundice or dark urine, or with a bone disorder, such as bone pain, can be a reason for the test.

ALP (Alkaline Phosphatase): symptoms of a high or low value

Low Levels

According to the Cleveland Clinic, a low alkaline phosphatase is less common than a high one, and may indicate malnutrition, a zinc or magnesium deficiency, an underactive thyroid, or rare genetic conditions such as hypophosphatasia and Wilson disease.

High Levels

According to the Cleveland Clinic, a high alkaline phosphatase from the liver may indicate, among other things, cholestasis of pregnancy, cirrhosis, hepatitis, a narrowed bile duct or a bile duct blockage caused by cancer; from the bones, among other things, a healing fracture, Paget's disease, osteomalacia, an overactive parathyroid or thyroid, or cancer spread to the bone. According to the Cleveland Clinic, signs of liver disease include jaundice, pain or swelling on the right side of the belly, bruising easily, nausea, dark urine and light-coloured stool; signs of a bone disorder include bone pain, joint pain and more frequent fractures. According to the Cleveland Clinic, untreated coeliac disease can also give a high value.

ALP (Alkaline Phosphatase): causes of a low or high value

What lowers the value

  • Malnutrition

    Malnutrition may lie behind a low alkaline phosphatase, which is less common than a high one.

  • Zinc or magnesium deficiency

    A zinc deficiency or a magnesium deficiency may cause a low alkaline phosphatase.

  • Underactive thyroid (hypothyroidism)

    An underactive thyroid may cause a low alkaline phosphatase.

  • Rare genetic conditions, such as hypophosphatasia

    Rare genetic conditions, including hypophosphatasia and Wilson disease, may cause a low alkaline phosphatase.

What raises the value

  • Narrowed or blocked bile ducts

    A narrowed bile duct, or a bile duct blocked by cancer, may cause a high alkaline phosphatase from the liver.

  • Hepatitis or cirrhosis of the liver

    Hepatitis, an inflammation of the liver, and cirrhosis may cause a high alkaline phosphatase.

  • Cholestasis of pregnancy

    Cholestasis of pregnancy is a liver disease that can develop late in pregnancy and may cause a high alkaline phosphatase.

  • Healing fracture

    A fracture that is healing may cause a high bone alkaline phosphatase.

  • Bone disorders such as Paget's disease or osteomalacia

    Paget's disease, a rare chronic bone disorder, and osteomalacia, which weakens the bones, may cause a high bone alkaline phosphatase.

ALP (Alkaline Phosphatase): lifestyle and this value

According to the Cleveland Clinic, an abnormal alkaline phosphatase does not necessarily mean a condition that needs treatment, because medicines such as birth control pills, diet, pregnancy and age can also affect the value. According to the Cleveland Clinic, with a high value the provider may order an isoenzyme test to determine where the excess enzyme is coming from. Discuss an abnormal value with your GP.

ALP (Alkaline Phosphatase): frequently asked questions

What is a normal alkaline phosphatase value?

According to the Cleveland Clinic, a normal alkaline phosphatase varies by laboratory, age and sex; Diagnostiek voor U uses 40 to 120 U/l for men and women above 18.

Why is alkaline phosphatase higher in children?

According to the Cleveland Clinic, alkaline phosphatase is typically raised in childhood and puberty because of bone growth and development.

ALP (Alkaline Phosphatase): sources

  1. den Elzen WPJ, Brouwer N, Thelen MH, Le Cessie S, Haagen I-A, Cobbaert CM. NUMBER: standardized reference intervals in the Netherlands using a 'big data' approach. Clin Chem Lab Med 2018;57(1):42-56. (retrieved 2026) doi.org
  2. Star-shl, Labbepalingen (referentiewaarden per bepaling), star-shl.nl, geraadpleegd 2026-10-01 (retrieved 2026) star-shl.nl
  3. Unilabs, Bepalingenklapper (referentiewaarden per bepaling), bepalingenklapper.nl, geraadpleegd 2026-10-01 (retrieved 2026) bepalingenklapper.nl
  4. Certe, Bepalingenwijzer (referentiewaarden per bepaling), bepalingenwijzer.certe.nl, geraadpleegd 2026-10-01 (retrieved 2026) bepalingenwijzer.certe.nl
  5. Diagnostiek voor U, eLabgids (Referentiewaarden DvU), diagnostiek.getincontrol.eu, geraadpleegd 2026-10-01 (retrieved 2026) diagnostiek.getincontrol.eu
  6. Cleveland Clinic Health Library, Alkaline Phosphatase (ALP), my.clevelandclinic.org, geraadpleegd 2026-10-18 (retrieved 2026) my.clevelandclinic.org

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ALP (Alkaline Phosphatase)

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