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Liver

Alkaline phosphatase in athletes

Alkaline phosphatase is an enzyme that in adults comes from two tissues. Those are the bile ducts inside the liver, and bone. For anyone training hard, that second source is the interesting one. Bone tissue is continuously broken down and rebuilt, and the enzyme is released during that rebuilding. This value is therefore not a measure of muscle damage. That is a common misreading on a report full of training markers. This page sets out what the value does and does not tell you about a trained body.

Doctor's Assessment Included

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: Nederlandse huisartsenpopulatie (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 this test measures

The test measures the total enzyme activity of alkaline phosphatase in blood, in u/l. Different tissues each make their own variant, an isoenzyme, and the standard test adds them up. Nothing is separated out.

Two of those variants matter to an athlete. The bone isoenzyme comes from osteoblasts, the cells that build new bone.

The liver isoenzyme comes from the epithelium of the small bile ducts. A single alkaline phosphatase value does not show which of the two has risen.

This is where training bloodwork often goes wrong. A report may show raised values of AST, CK and alkaline phosphatase side by side. That looks like one story.

It is not. AST and CK leak from loaded muscle fibres. Alkaline phosphatase does not, because muscle tissue is not a source of this enzyme.

MarkerWhere a rise comes fromResponds to heavy training
CKskeletal muscleyes, strongly and quickly
ASTmuscle and liveryes, moderately
Alkaline phosphatasebone and bile ductsindirectly, through bone turnover
Gamma-GTliver and bile ductsno

The reference bands come from NUMBER, the harmonisation project run by the NVKC. For men aged 19 to 50 the band runs from 45 to 128 u/l. For women in that group it is 38 to 123 u/l. Your own laboratory's limits remain decisive.

ALP (Alkaline Phosphatase): why this value matters

A raised alkaline phosphatase in a trained athlete asks exactly one question. Did this come from bone or from the bile ducts. You answer it with gamma-GT, because that enzyme sits in the liver and not in bone.

Does gamma-GT stay normal while alkaline phosphatase in the blood is raised? Then the rise probably comes from bone tissue.

In an athlete that is often well explained. A healing stress fracture raises the value for weeks. The same is true after an ordinary fracture.

There is also a slower route, and it is less innocent. A low vitamin D raises bone turnover, and with it this enzyme. That is a real pattern in athletes who train indoors or get little daylight. Low energy availability at high training volumes belongs in the same conversation.

The conclusion this page wants to prevent is the reflex to schedule a rest week. A deload lowers CK, because CK comes from muscle. On a bone-driven alkaline phosphatase, rest does not have that effect.

You change nothing. The real question stays open.

If gamma-GT does rise alongside, the conversation shifts to bile flow. Read the result then together with AST and direct bilirubin.

ALP (Alkaline Phosphatase): when is testing worthwhile?

Alkaline phosphatase is a standard part of a liver panel. Most athletes therefore meet the value without having asked for it.

Measuring it deliberately makes sense in three situations. After a stress fracture or an ordinary fracture, to weigh how recovery is going.

With persistent bone or shin pain that does not fit a known injury. And with a known low vitamin D, where bone turnover may already be raised.

Always request the test together with gamma-GT. Without that second enzyme a raised result cannot be placed, and the measurement yields nothing usable.

Timing around training deserves attention. For this enzyme itself a hard session is no problem, because muscle is not a source.

If the test is done alongside CK and AST, it is: those two rise sharply after loading. Schedule the draw 48 hours after a hard session.

Fasting is usually not required for this test. It still helps. In blood groups O and B, the intestinal form rises after a fatty meal.

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

Low Levels

A low value causes no symptoms and is almost always found by chance.

In athletes the context is still worth looking at. Persistently low values can accompany a zinc or magnesium deficiency. An underactive thyroid belongs here too.

So does a long-standing energy intake that is too low. That last pattern occurs at high training volumes with a tight diet. It affects more than this one enzyme.

Rare causes are Wilson's disease and hypophosphatasia, an inherited condition in which the enzyme itself falls short. Bone pain and fractures under light loading belong with it.

One low result without symptoms is no reason to act. If the value stays low, discuss it with your doctor.

High Levels

With a mildly raised value most athletes notice nothing. The abnormality shows up in the bloodwork, not in training.

Where there are symptoms, they often point to the source. Bone pain that carries on at night fits a bone cause. So does tenderness at one point of the shin.

So does pain that returns as soon as loading goes back up. A fracture after a fall too light to explain it belongs in the same group.

With a bile-duct cause the picture is different. Think of itching without a rash and yellowing of skin or the whites of the eyes. Dark urine and pale stools belong here too.

A drop in performance or recovery is not a symptom of this enzyme. That comes from the underlying cause, or from something else on the report.

ALP (Alkaline Phosphatase): what to do about an abnormal value

Male

If Low

Low ALP is generally not concerning.

If High

Elevated ALP may indicate bile duct or bone problems. Consider further evaluation.

Female

If Low

Low ALP is generally not concerning.

If High

Elevated ALP may indicate bile duct or bone problems. Consider further evaluation.

ALP (Alkaline Phosphatase): lifestyle and this value

This number cannot be steered directly. What can be steered are the two tissues that feed it.

For bone, loading is the most powerful instrument you have. Jumping, sprinting and heavy lifting put a stimulus on bone formation that endurance running alone does not. Also make sure of enough calcium and vitamin D, and enough energy intake around high training volumes.

For the liver and bile ducts the ordinary rules apply: limit alcohol and keep a healthy weight. Take medication as prescribed. Report long-term use of painkillers or supplements to your doctor.

Three things that do not work. A deload does not lower a bone-driven value. Rest touches the muscle side, not the bone side.

High-dose vitamin D on your own initiative is no answer to a raised result alone. And one measurement is not a conclusion: repeat the test before adjusting your programme.

Schedule a new draw fasting, at least two days after a hard session.

Note which phase of your season you are in as well. A build block and a recovery week give very different pictures. Without that note you will compare two numbers a year apart with no context.

ALP (Alkaline Phosphatase): frequently asked questions

Does alkaline phosphatase rise from heavy training?
Not directly. Muscle tissue does not make this enzyme. A hard session therefore does not lift the value the way it lifts CK. Indirectly it can. Heavy bone loading and recovery from a stress fracture raise bone turnover, and with it the result.
Is this enzyme a measure of muscle damage?
No, and that is the main misconception this page addresses. CK is the muscle marker, and AST comes from muscle and liver. Alkaline phosphatase comes from bone and bile ducts, so muscle damage leaves the value untouched.
My alkaline phosphatase is raised, should I schedule a deload?
Not on this number alone. Rest lowers muscle markers, but not a bone-driven result. Have gamma-GT measured first to separate bone from bile ducts. Only then make a decision about loading.
Does a healing stress fracture cause a raised value?
Yes. During bone repair osteoblasts work at full capacity, and that raises the enzyme for weeks. The value falls gradually as healing progresses. For that reason alone it is a poor measure of what that bone can take.
Can a low vitamin D push this value up?
Yes. With a deficiency bone turnover increases, and the enzyme rises with it. That is a real pattern in athletes who train indoors or get little daylight. It is worth investigating further.
How long after training should I have blood drawn?
For this enzyme it matters little, because muscle is not a source. Are CK or AST measured at the same time? Then schedule the draw 48 hours after a hard session. Otherwise you read training noise instead of your baseline.

Test Products

This marker is included in the following test panels.

Whoop

Whoop Metabolic Health

A 51-biomarker metabolic panel inspired by the WHOOP Metabolic Health Panel — blood sugar regulation, insulin, thyroid, liver and the mineral cofactors behind your metabolism.

Complete Blood Count (CBC) Leukocyte Differential ALP (Alkaline Phosphatase) ALT (Alanine Aminotransferase) AST (Aspartate Aminotransferase) Albumin Total Protein Bilirubin (Total) ApoB (Apolipoprotein B) Total Cholesterol LDL Cholesterol HDL Cholesterol Triglycerides Lipoprotein(a) Urea (BUN) Creatinine eGFR (Estimated Glomerular Filtration Rate) Calcium Bicarbonate Chloride Sodium Potassium Magnesium Cortisol DHEA-S Estradiol (E2) FSH (Follicle Stimulating Hormone) LH (Luteinizing Hormone) SHBG (Sex Hormone Binding Globulin) Total Testosterone Free Testosterone TSH (Thyroid Stimulating Hormone) Glucose (Fasting) HbA1c (Glycated Hemoglobin) Insulin (Fasting) HOMA-IR CRP (C-Reactive Protein) Homocysteine Ferritin Iron (Serum) Transferrin Transferrin Saturation Vitamin D (25-OH) Leptin Zinc Selenium Iodine Copper Free T3 (Triiodothyronine) Free T4 (Thyroxine) GGT (Gamma-Glutamyl Transferase)
€799,-
Whoop

Whoop

A 43-biomarker comprehensive health panel inspired by WHOOP Advanced Labs — a deep look at metabolism, cardiovascular risk, hormones, liver, kidney and inflammation.

SHBG (Sex Hormone Binding Globulin) TSH (Thyroid Stimulating Hormone) ALT (Alanine Aminotransferase) LDL Cholesterol Cortisol DHEA-S Estradiol (E2) Free Testosterone FSH (Follicle Stimulating Hormone) LH (Luteinizing Hormone) Total Testosterone Bicarbonate Calcium Chloride Ferritin Iron (Serum) Magnesium Potassium Sodium Transferrin CRP (C-Reactive Protein) Homocysteine Glucose (Fasting) HbA1c (Glycated Hemoglobin) ApoB (Apolipoprotein B) HDL Cholesterol Total Cholesterol Albumin HOMA-IR ALP (Alkaline Phosphatase) AST (Aspartate Aminotransferase) Bilirubin (Total) Total Protein Urea (BUN) Creatinine Vitamin D (25-OH) eGFR (Estimated Glomerular Filtration Rate) Insulin (Fasting) Leukocyte Differential Transferrin Saturation Lipoprotein(a) Triglycerides Basic Blood Count
€499,-
Whoop

Whoop Heart Health

A 45-biomarker heart health panel inspired by the WHOOP Heart Health Panel — an advanced look at cholesterol, lipoproteins, inflammation and kidney function.

Complete Blood Count (CBC) Leukocyte Differential ALP (Alkaline Phosphatase) ALT (Alanine Aminotransferase) AST (Aspartate Aminotransferase) Albumin Total Protein Bilirubin (Total) ApoB (Apolipoprotein B) Total Cholesterol LDL Cholesterol HDL Cholesterol Triglycerides Lipoprotein(a) Urea (BUN) Creatinine eGFR (Estimated Glomerular Filtration Rate) Calcium Bicarbonate Chloride Sodium Potassium Magnesium Cortisol DHEA-S Estradiol (E2) FSH (Follicle Stimulating Hormone) LH (Luteinizing Hormone) SHBG (Sex Hormone Binding Globulin) Total Testosterone Free Testosterone TSH (Thyroid Stimulating Hormone) Glucose (Fasting) HbA1c (Glycated Hemoglobin) Insulin (Fasting) HOMA-IR CRP (C-Reactive Protein) Homocysteine Ferritin Iron (Serum) Transferrin Transferrin Saturation Vitamin D (25-OH) Cystatin C Uric Acid
€629,-
Whoop

Whoop Performance Health

A 50-biomarker performance panel inspired by the WHOOP Performance Health Panel — recovery, blood production, thyroid, hormones, iron and nutrient status for people who train.

Complete Blood Count (CBC) Leukocyte Differential ALP (Alkaline Phosphatase) ALT (Alanine Aminotransferase) AST (Aspartate Aminotransferase) Albumin Total Protein Bilirubin (Total) ApoB (Apolipoprotein B) Total Cholesterol LDL Cholesterol HDL Cholesterol Triglycerides Lipoprotein(a) Urea (BUN) Creatinine eGFR (Estimated Glomerular Filtration Rate) Calcium Bicarbonate Chloride Sodium Potassium Magnesium Cortisol DHEA-S Estradiol (E2) FSH (Follicle Stimulating Hormone) LH (Luteinizing Hormone) SHBG (Sex Hormone Binding Globulin) Total Testosterone Free Testosterone TSH (Thyroid Stimulating Hormone) Glucose (Fasting) HbA1c (Glycated Hemoglobin) Insulin (Fasting) HOMA-IR CRP (C-Reactive Protein) Homocysteine Ferritin Iron (Serum) Transferrin Transferrin Saturation Vitamin D (25-OH) IGF-1 (Insulin-like Growth Factor) Creatine Kinase (CK) Reticulocytes Free T3 (Triiodothyronine) Free T4 (Thyroxine) Vitamin B12 Folate (Folic Acid)
€689,-
Whoop

Whoop Women's Health

A 53-biomarker women's health panel inspired by the WHOOP Women's Health Panel — fertility, cycle and thyroid hormones plus a complete metabolic and nutrient base.

Complete Blood Count (CBC) Leukocyte Differential ALP (Alkaline Phosphatase) ALT (Alanine Aminotransferase) AST (Aspartate Aminotransferase) Albumin Total Protein Bilirubin (Total) ApoB (Apolipoprotein B) Total Cholesterol LDL Cholesterol HDL Cholesterol Triglycerides Lipoprotein(a) Urea (BUN) Creatinine eGFR (Estimated Glomerular Filtration Rate) Calcium Bicarbonate Chloride Sodium Potassium Magnesium Cortisol DHEA-S Estradiol (E2) FSH (Follicle Stimulating Hormone) LH (Luteinizing Hormone) SHBG (Sex Hormone Binding Globulin) Total Testosterone Free Testosterone TSH (Thyroid Stimulating Hormone) Glucose (Fasting) HbA1c (Glycated Hemoglobin) Insulin (Fasting) HOMA-IR CRP (C-Reactive Protein) Homocysteine Ferritin Iron (Serum) Transferrin Transferrin Saturation Vitamin D (25-OH) AMH (Anti-Müllerian Hormone) Progesterone Prolactin TPO Antibodies Free T3 (Triiodothyronine) Free T4 (Thyroxine) Leptin Vitamin B12 Folate (Folic Acid) Phosphorus
€709,-
Whoop

Whoop Men's Health

A 48-biomarker men's health panel inspired by the WHOOP Men's Health Panel — testosterone, PSA and prostate health plus a complete metabolic and hormone base.

Complete Blood Count (CBC) Leukocyte Differential ALP (Alkaline Phosphatase) ALT (Alanine Aminotransferase) AST (Aspartate Aminotransferase) Albumin Total Protein Bilirubin (Total) ApoB (Apolipoprotein B) Total Cholesterol LDL Cholesterol HDL Cholesterol Triglycerides Lipoprotein(a) Urea (BUN) Creatinine eGFR (Estimated Glomerular Filtration Rate) Calcium Bicarbonate Chloride Sodium Potassium Magnesium Cortisol DHEA-S Estradiol (E2) FSH (Follicle Stimulating Hormone) LH (Luteinizing Hormone) SHBG (Sex Hormone Binding Globulin) Total Testosterone Free Testosterone TSH (Thyroid Stimulating Hormone) Glucose (Fasting) HbA1c (Glycated Hemoglobin) Insulin (Fasting) HOMA-IR CRP (C-Reactive Protein) Homocysteine Ferritin Iron (Serum) Transferrin Transferrin Saturation Vitamin D (25-OH) PSA (Prostate-Specific Antigen) Prolactin Leptin Uric Acid Zinc
€659,-

Medical reviewer

Medical standards

Dr. Naimi oversees the medical standards behind our content and assessments.

Medical policy
CIBG Ministerie van Volksgezondheid,
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ALP (Alkaline Phosphatase)

€8,-