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Osteomalacia

What is osteomalacia?

Osteomalacia is the softening of bones in the body, leading to bone pain, bone tenderness, bending of the long bones and, at times, even fractures.

Although bone appears to be hard, it is mostly made of collagen, the same material that flexible body parts like skin and tendons are made from. Bones become hard when a mineral, calcium phosphate, coats the collagen fibres in a process called mineralization. The more mineral in the bone, the harder the bone is.[1]

New bone is being formed in the body all the time. If the new collagen fibres are not properly coated with mineral, the bones become soft and may bend and break. This condition is known as osteomalacia.[2]

The most common cause of osteomalacia is a lack of vitamin D. In the United States, incidences of osteomalacia are rare, depending on location. People who live in cooler climates, particularly people with darker skin, are more at risk of developing osteomalacia.

In most cases, the prognosis is good, and the condition can be cured with straightforward treatment, often involving a course of vitamin and/or mineral supplements.

Symptoms of osteomalacia

Soft bones are a typical sign of osteomalacia. It can lead to symptoms such as:[3][4][5]

  • Pain or tenderness in the bones
  • Muscle spasms and/or cramps
  • Muscle weakness, particularly in the thighs and buttocks
  • Waddling gait and/or difficulty walking
  • Feeling of pins and needles (paresthesia) or numbness around the mouth or in the arms and legs, in cases of calcium deficiency

Very severe cases of osteomalacia may result in:

  • Bone deformity, i.e. bending of the long bones
  • Pseudofractures, known as Looser’s zones, particularly in bones that bear weight such as the feet and pelvis
  • Fractures of bones, especially after an event that would not usually cause such severe consequences, e.g. a non-severe fall in a middle-aged person

Osteomalacia is sometimes confused with other conditions which involve signs of weakening of bones, specifically rickets, osteoporosis and osteopenia. See these resources on rickets and osteoporosis for more information.

Causes of osteomalacia

The causes that lead to the development of osteomalacia are most commonly not getting enough vitamin D and/or phosphorus. Although vitamin D deficiency is increasing in some countries, this does not always lead to osteomalacia.[6]

There are rare forms of osteomalacia that are caused by genetic factors or conditions that affect the body’s ability to absorb vitamin D or phosphorus, such as liver disease, kidney failure or coeliac disease.[7]

Lack of calcium can also cause osteomalacia, but, in Western countries, it’s rare for people to have a calcium deficiency.[7]

Vitamin D deficiency and osteomalacia

Vitamin D is important for healthy bones because it encourages the body to absorb calcium and phosphorus.[8] The body makes vitamin D when ultraviolet (UVB) waves, which are found in sunlight, directly touch the skin, interacting with the body’s chemistry to form vitamin D3.[9]

People who live in climates with seasons lacking strong sunshine, such as autumn and fall in the northern hemisphere, or who are unable to get direct sunlight on their skin, will not produce enough vitamin D to create the minerals which harden bones.[10] This increases a person’s risk of developing osteomalacia.

See this resource on vitamin D deficiency for more information.

Phosphate deficiency

Less common forms of osteomalacia are caused by conditions that affect the body’s ability to absorb phosphates. These include:[11]

  • Rare genetic defects
  • Kidney disease, though more common in advanced stages, and kidney failure
  • Liver disease

Certain drugs

Some medications can increase the risk of osteomalacia when taken for a long time and/or in higher dosages.

Some older epilepsy medications linked to osteomalacia include:[12]

  • Sodium valproate
  • Carbamazepine
  • Phenobarbital
  • Topiramate
  • Phenytoin

Other medications that are associated with osteomalacia include:[13] - Cholestyramine, used to reduce cholestero - Rifampicin, an antibioti - Isoniazid, used for treating tuberculosi - Antacids containing aluminu - Saccharated ferric oxide, used to treat anemi - Biophosphonates, used to treat osteoporosis and bone metastase - Fluoride, used to prevent tooth decay

Who is at risk of osteomalacia

People who live in cooler climates, where there isn’t much sunlight during the autumn or fall, are at risk of developing osteomalacia.[14]

Anyone who covers most of their skin when they go outside, uses very strong sunscreen or can’t get outside due to illness or disability, is unlikely to be able to make enough vitamin D from sunlight, even in spring or early summer.[5]

People with dark skin, who live in countries without strong sunlight, are particularly at risk. This is because darker skin does not make as much vitamin D as lighter skin.(^10]

Lactose-intolerant people may not get enough calcium and vitamin D in their diets to produce strong bones, and so may need to consume other foods high in calcium and vitamin D instead.[5]

See this resource on vitamin D for more information.

Diagnosing osteomalacia

Osteomalacia can be diagnosed with a blood test measuring levels of calcium, vitamin D and phosphate in the body.[15] X-rays, CT and MRI scans can detect bone fractures.

Treatment and prevention of osteomalacia

Osteomalacia is treatable, usually with vitamin and/or mineral supplements, and most people can be cured. It is generally treated by administration of vitamin D, calcium and, if needed, also phosphorus.[5]

If the osteomalacia is caused by an underlying condition, this will also need to be treated. Osteomalacia caused by phosphate deficiency is usually due to another condition. Treatment will be recommended by a doctor.[4]

Bone will begin to strengthen within a few weeks to a few months and should be fully healed within six months. However, pain and muscle weakness may continue to be experienced during the healing process.[5][16][17]

Vitamin and mineral supplements

The amount of supplementary vitamin D a person may require depends on factors such as their age, how much natural sunlight they receive where they live and any possible other influencing factors, like having certain medical conditions or taking certain drugs that influence how the body takes up, processes or builds vitamin D.

For people living in the United States, the National Academies of Science, Engineering and Medicine recommends the following daily intakes for adults:[18]

  • Vitamin D: 600 IU (international units) / 15 mcg a day
  • Calcium: 1,000 mg a day
  • Phosphorus: 700 mg a day

For people living in the U.K., the NHS recommends 400 IU / 10 mcg of vitamin D per day for adults. During summer, the NHS advises that most people should be able to make enough vitamin D from sunlight, given enough sun exposure, and diet.

See this resource on vitamin D deficiency for more information.

If a person’s calcium intake from diet is less than 750 mg a day, supplements of 500-1,000 mg a day can help speed up the process of restoring bone.[17] Do not take more than 1500 mg of calcium supplements a day without consulting a doctor, as this could lead to unwanted side effects.[19]

Sources of vitamin D in food

Another way of getting vitamin D is through diet, though it does not occur in many foodstuffs. Vitamin D is found in foods such as:

  • Oily/fatty fish
  • Liver
  • Egg yolks
  • Cheese
  • Foods fortified during the manufacturing process

See this resource on vitamin D for more information.

Maintaining healthy bones

There are many things people can do in day-to-day life to promote healthy bones. These include:[20]

  • Having a diet rich in vitamin D
  • Getting a healthy amount of sunshine
  • Reducing alcohol intake
  • Stopping smoking
  • Exercising regularly
  • Maintaining a healthy weight

Other medications that are associated with osteomalacia include:[13]

  • Cholestyramine, used to reduce cholesterol
  • Rifampicin, an antibiotic
  • Isoniazid, used for treating tuberculosis
  • Antacids containing aluminum
  • Saccharated ferric oxide, used to treat anemia
  • Biophosphonates, used to treat osteoporosis and bone metastases
  • Fluoride, used to prevent tooth decay

Osteomalacia FAQs

Q: Are osteomalacia and osteoporosis the same thing?
A: No. Osteomalacia is the softening of bones, usually due to a lack of vitamin D. Osteoporosis is when bones lose density and become brittle, usually because of age or hormone related changes. While the signs and symptoms of both conditions may be similar, the underlying causes and treatments are different.

Q: Are osteomalacia and rickets the same thing?
A: Yes, the only difference is the age of the person with the condition. Osteomalacia in children is called rickets, but its cause, symptoms and treatment are the same. Children with rickets are at a much higher risk of developing skeleton abnormalities because they are still growing.[21]

Q: Are osteomalacia and osteopenia the same thing?
A: No. Osteopenia is similar to osteoporosis in that it is caused by loss of bone density, but isn’t severe enough to be classed as osteoporosis.[22]

Q: Can osteomalacia cause osteoporosis?
A: No. Osteoporosis is caused by the bones losing density, usually due to the ageing process and/or hormonal changes in postmenopausal women.

Q: Can osteomalacia be reversed?
A: Yes. Bone is being renewed all the time, and getting enough of the right vitamins and minerals will allow normal mineralization to occur. (See What is osteomalacia?) The process takes around six months. (See Treatment and prevention)

Q: Can osteomalacia be prevented?
A: Yes. Getting enough vitamin D, calcium and phosphorus, adapted to the special needs of someone with liver or kidney disease if necessary, will prevent osteomalacia.


  1. National Institute of Arthritis and Musculoskeletal and Skin Diseases. “What Is Bone?” Accessed April 5, 2018.

  2. Arthritis Research UK. “What is osteomalacia?” Accessed April 5, 2018.

  3. Amboss. “Osteomalacia and rickets, subdivision: clinical features.” January 2018. Accessed April 25, 2018.

  4. Hypopara UK. “Osteomalacia.” July 2008. Accessed April 5, 2018.

  5. MedlinePlus. “Osteomalacia.” March 2018. Accessed April 5, 2018.

  6. JAMA Internal Medicine. “Demographic Differences and Trends of Vitamin D Insufficiency in the US Population, 1988-2004.” March 2009. Accessed April 5, 2018.

  7. Arthritis UK. “What causes osteomalacia?” Accessed April 5, 2018.

  8. National Center for Biotechnology Information. “Bone Health and Osteoporosis: A Report of the Surgeon General: The Basics of Bone in Health and Disease.” 2004. Accessed April 5, 2018.

  9. National Institutes of Health. “Vitamin D.” March 2018. Accessed April 5, 2018.

  10. The Journal of Nutrition. “Vitamin D and African Americans.” April 2006. Accessed April 5, 2018.

  11. National Center for Biotechnology Information. “Bone Health and Osteoporosis: A Report of the Surgeon General: Diseases of Bone.” 2004. Accessed April 5, 2018.

  12. Epilepsy Action. “Osteoporosis and epilepsy.” August 2016. Accessed April 5, 2018.

  13. US National Library of Medicine. “Drug-induced osteomalacia.” October 1998. Accessed April 26, 2018.

  14. Arthritis UK. “Who gets osteomalacia?” Accessed April 5, 2018.

  15. Arthritis UK. “How is osteomalacia diagnosed?” Accessed April 5, 2018.

  16. Patient Info. “Vitamin D Deficiency including Osteomalacia and Rickets.” June 2015. Accessed April 5, 2018.

  17. Arthritis UK. “What treatments are there for osteomalacia?” Accessed April 5, 2018.

  18. The National Academies of Science, Engineering and Medicine. “Dietary Reference Intakes for Vitamin C, Vitamin E, Selenium, and Carotenoids.” August 2000. Accessed April 5, 2018.

  19. NHS Choices. “Calcium.” March 2017. Accessed April 26, 2018.

  20. Arthritis UK. “Self-help and daily living for arthritis.” Accessed April 26, 2018.

  21. The Royal Children’s Hospital Melbourne. “Rickets.” January 2014. Accessed April 5, 2018.

  22. MedlinePlus. “Bone Density.” March 2015. Accessed April 5, 2018.