Alkaline Phosphatase (ALP)

July 21, 2020

What is Alkaline phosphatase (ALP)?

Alkaline phosphatase (ALP) is an enzyme predominantly found in the liver and bone. It is also found in smaller amounts in the kidneys, intestines and the placenta in pregnant women. Different parts of the body produce different forms of ALP called isoenzymes.[1]

​Why take an Alkaline Phosphatase blood test?

If levels are high, an alkaline phosphatase blood test can help to identify bone or liver disorders. If other liver tests such as alanine aminotransferase and bilirubin are also raised, then this is usually indicative of liver issues. The liver is a major organ which is responsible for filtering the blood from the digestive tract as well as detoxifying chemicals and metabolising drugs. Therefore, it is important to check it is working effectively and is healthy, particularly if you have an unhealthy diet or lead a sedentary lifestyle.[2]

If ALP levels are low then this can indicate magnesium deficiency, hypothyroidism, osteoporosis, malnutrition and myelogenous leukaemia. Although reduced levels are less common, the female contraceptive pill can also lower blood levels of the enzyme.[3]

You can test your ALP levels by purchasing a simple at-home finger prick test kit which is then analysed at an accredited lab. Forth offers a number of blood tests which include ALP such as a liver function test or our bestselling Baseline Plus blood test which tests 20 biomarkers integral to good health.

What function does Alkaline Phosphatase have in the body?

ALP is found in most tissues in the body but is mostly present in the liver and bone. These two forms of ALP are the predominate isoenzymes of ALP in the blood. ALP has several functions within the human body. The enzyme has an important role in metabolism in the liver as well as the development of the skeleton. Hence, it’s used within diagnostics for both liver and bone.

How do changes in Alkaline Phosphatase affect health and wellbeing?

Raised ALP levels can signify liver injury which in severe cases can result in flu-like symptoms. If the liver is unable to function appropriately then it can cause a build-up of toxins within the body which can leave you feeling quite unwell.

Equally, in bone health, raised ALP levels may be a sign of vitamin D deficiency. You may be unaware you are deficient in vitamin D but it will affect bone health and may result in conditions such as osteomalacia.

Reduced levels of ALP are less common but if levels are reduced then malnutrition, anaemia or osteoporosis can cause this. As a result, fatigue and low energy levels are common symptoms. Therefore, a major consequence of this is not feeling able to carry out normal daily activities or a lack of motivation which can subsequently impact on your mental health.

If you are worried about your ALP level or just want to check where you fall on the range, you can test your level with a simple at-home blood test.

What Can Cause Alkaline Phosphatase To Change?

There are several factors responsible for causing ALP levels to change. Although some reasons may be harder to control, making healthy lifestyle changes can help to keep ALP levels within a normal range.

Research has identified the expression of an ALP isozyme in fat cells (adipocytes), which has been shown to increase fat deposition during adipogenesis (a form of cell differentiation whereby pre-adipocytes become adipocytes. Therefore, ALP may be a precursor for adipocytes and may play a significant role in adipogenesis. However, the link between ALP and obesity requires further research.[4]

If ALP levels are raised due to vitamin D deficiency, this is usually a result of a lack of sunlight exposure. Vitamin D is primarily made because of exposure to UVB radiation in sunlight or alternatively, it can be ingested by various food sources.[5]

Gallstones are linked to an increase in ALP levels, particularly if a gallstone becomes trapped in a duct.


What Are The Most Common Symptoms?

The most common symptoms associated with vitamin D deficiency are:

  • Muscle weakness
  • Fatigue
  • Greater susceptibility to illness
  • Depression

Symptoms associated with gallstones are:

  • Severe pain
  • Fever
  • Jaundice

The most common symptoms of liver damage are:

  • Feeling tired and weak all or most of the time
  • Reduced appetite
  • Loss of libido
  • Jaundice (yellowing of the skin and whites of the eyes
  • Itchy skin
  • Nausea and/or vomiting[6]

How to keep Alkaline Phosphatase in the healthy range

Diet is a major factor in the health of the liver. The liver has important functions in the human body including the detoxification of chemicals, metabolism of drugs and blood filtration. Individuals with non-alcoholic fatty liver disease tend to eat highly calorific diets which mainly consist of carbohydrates and fats.[7] Likewise, diet can be a major factor in the development of gallstones. Therefore, it is essential to eat a healthy, balanced diet to ensure the liver and gallbladder remain healthy.  Make sure you are eating a good amount of dietary fibre as this will help to keep your digestive tract healthy, the liver filters the blood from the digestive tract. Good sources of fibre are fruit, vegetables and whole grains. Eating lots of simple carbohydrates like white bread, cakes and pastries can increase blood glucose levels rapidly and lead to weight gain, so you need to be aware of how much you are eating. Swapping simple carbohydrates for wholegrains will slow down the rise in blood sugar, are healthier for the liver and are high in fibre.[8]

Gallstones occur because of an imbalance in the chemical composition of bile within the gallbladder. Although they are relatively common, gallstones are more common if you are:

  • overweight/obese
  • over 40 years of age
  • female

Ensure you are getting enough vitamin D by exposing your skin to sunlight. It is recommended from March to October you spend around 15 minutes per day in the sun to ensure your vitamin D levels are adequate. In the UK, over half of the adult population has insufficient levels of vitamin D.[9] Therefore, you may wish to consider a vitamin D supplement to top up which should contain at least 10mcg of vitamin D. [10]

Exercise has many benefits for both health and wellbeing. For example, exercise is great for depression, self-esteem and anxiety as it releases endorphins and ‘feel good’ factors. Plus, exercise also has social benefits by encouraging you to meet new people and even exercise with existing friends and family. There is also strong evidence which shows there are significant benefits of regular exercise on the overall health of the body, particularly the cardiovascular system. Recommendations state that we should all aim to complete at least 150 minutes of aerobic exercise per week such as running, jogging or exercise classes.

- Health scores calculated



[1] Lab Tests Online. (2019). Alkaline Phosphatase (ALP) Test. Available at:

[2] British Liver Trust. (2019). Liver Health. Available at:

[3] Sharma, U., Pal, D and Prasad, R. (2014). Alkaline Phosphatase: An Overview. Indian Journal of Clinical Biochemistry: 29(3), pp 269-278.

[4] Khan, A, R et al. (2015). Elevated Serum Level of Human Alkaline Phosphatase in Obesity. J Pak Med Assoc: 65(11), pp 1182-1185.

[5] Kennel, K, A et al. (2010). Vitamin D Deficiency in Adults: When to Test and How to Treat. Mayo Clin Proc: 85(8), pp 752-758.

[6] National Health Service. (2017).  Liver Disease. Available at:

[7] Nseir, W et al. (2014). Role of Diet and Lifestyle Changes in Nonalcoholic Fatty Liver Disease. World Journal of Gastroenterology: 20(28), pp 9338-9344.

[8] (2019). Carbohydrate and Diabetes. Available at:

[9] Pearce, S, H, S and Cheetham, T, D. (2010). Diagnosis and Management of Vitamin D Deficiency. BMJ: 340.

[10] National Health Service – Vitamin D.

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This information has been medically reviewed by Dr Nicky Keay

Nicola has extensive clinical and research experience in the fields of endocrinology and sport and exercise medicine. Nicky is a member of the Royal College of Physicians, Honorary Fellow in the Department of Sport and Exercise Sciences at Durham University and former Research Fellow at St. Thomas' Hospital.

Dr Nicky Keay

Dr Nicky Keay

BA, MA (Cantab), MB, BChir, MRCP.