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Liver

Alkaline phosphatase (ALP) in women: pregnancy, the pill and the value

Alkaline phosphatase is an enzyme that according to the Cleveland Clinic exists in the liver, bile ducts, bones, kidneys and intestines, and during pregnancy also in the placenta. An enzyme is a protein inside a cell through which certain bodily processes can take place; in the blood this enzyme comes mainly from the liver and the bones.

According to the Cleveland Clinic, the value can be higher during pregnancy, and cholestasis of pregnancy, a liver disease that can develop late in pregnancy, is among that source's liver causes of a high value, while according to that source a value that is too low may indicate an underactive thyroid, among other things. Only a blood test shows how high the alkaline phosphatase is.

Unilabs uses 38 to 123 U/l for women aged 19 to 50 and 48 to 142 U/l for women aged 51 to 65.

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
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 · Female · 19–50 years 38–123 U/l
38 123
Star-shl · Female · 51–65 years 48–142 U/l
48 142
Star-shl · Female · 66–80 years 47–138 U/l
47 138
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
Certe · Female · 19 years and older · a limit, not a range < 98 U/L
98
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

An alkaline phosphatase measurement gives the amount of the enzyme in U/l, and Unilabs gives women their own limit per age group, such as 47 to 138 U/l from 66 to 80.

ALP (Alkaline Phosphatase): why this value matters

Alkaline phosphatase matters in pregnancy, because according to the Cleveland Clinic a rise can then be linked to the placenta, but also to cholestasis of pregnancy.

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
Complete Metabolic Panel · €149,-
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, signs of possible liver disease, such as jaundice, belly pain especially on the right side, or dark urine and light-coloured stool, are a reason a provider may order an ALP test.

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

Low Levels

According to the Cleveland Clinic, an abnormally low alkaline phosphatase is less common than a raised one and may indicate, among other things, hypothyroidism, an underactive thyroid, and rare genetic conditions such as hypophosphatasia.

High Levels

According to the Cleveland Clinic, pregnancy, birth control pills and age can affect alkaline phosphatase without there being a condition. According to that source, a high value may also indicate cholestasis of pregnancy, hepatitis or a bone disorder.

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

With an abnormal alkaline phosphatase, tell your GP whether you are pregnant or take the pill, because according to the Cleveland Clinic both can affect the value.

ALP (Alkaline Phosphatase): frequently asked questions

Is alkaline phosphatase higher during pregnancy?

According to the Cleveland Clinic, alkaline phosphatase may be higher during pregnancy, because the enzyme also exists in the placenta.

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. Unilabs, Bepalingenklapper (referentiewaarden per bepaling), bepalingenklapper.nl, geraadpleegd 2026-10-01 (retrieved 2026) bepalingenklapper.nl
  3. Certe, Bepalingenwijzer (referentiewaarden per bepaling), bepalingenwijzer.certe.nl, geraadpleegd 2026-10-01 (retrieved 2026) bepalingenwijzer.certe.nl
  4. Diagnostiek voor U, eLabgids (Referentiewaarden DvU), diagnostiek.getincontrol.eu, geraadpleegd 2026-10-01 (retrieved 2026) diagnostiek.getincontrol.eu
  5. Star-shl, Labbepalingen (referentiewaarden per bepaling), star-shl.nl, geraadpleegd 2026-10-01 (retrieved 2026) star-shl.nl
  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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