From BUPA July 2008
This factsheet is for people who have osteomalacia, or who would like information about it.
Osteomalacia is a condition that affects your bones. It makes them soft and weak, and can make you more prone to fractures. It's usually caused by a deficiency in vitamin D.
Throughout your lifetime, your bones are continually maintaining and repairing themselves. This is done through a process called "bone turnover", in which tiny areas of bone are removed and replaced so that old bone can be swapped for new bone.
The strength of your bones depends on the amount of minerals that are laid down in them. This is done through a process called mineralisation. Minerals such as calcium and phosphorus are taken from the food you eat and deposited in your bones. This process is assisted by vitamin D which helps the body to absorb calcium and make sure it gets to where it's needed. During childhood, mineralisation ensures that bones grow and develop, whereas in adulthood it maintains and repairs them.
Osteomalacia happens when your bones don't get enough of the minerals they need. This makes them soft and weak, and can cause them to crack or break more easily. It can also cause bone deformities.
Osteomalacia only affects adults. If children have soft bones, the condition is called rickets.
Symptoms of osteomalacia
The symptoms of osteomalacia can be quite vague - you may just feel generally unwell. However, symptoms to look out for include:
If you had rickets as a child, you may notice that any existing bone deformities that you have (eg "knock-knees" or a hunched back) get worse.
Osteomalacia can be caused by other underlying conditions, such as kidney or liver disease. Often it's the symptoms of these other conditions that are picked up first and later lead to a diagnosis of osteomalacia.
Complications of osteomalacia
If you have very low levels of calcium in your body, you may develop hypocalcaemia. Hypocalcaemia can make the symptoms of osteomalacia much worse and cause fractures. Symptoms include:
If you have any of these symptoms, you should see your GP.
If you have osteoporosis (when your bones are porous and less dense than healthy bones) and osteomalacia, you are more at risk of fractures.
Causes of osteomalacia
Vitamin D deficiency
Osteomalacia is most often caused by a prolonged lack of vitamin D. Vitamin D comes from two main sources: sunlight, which accounts for 80 percent of the vitamin D you need, and your diet from which you get the remaining 20 percent.
In the UK over one in ten adults are deficient in vitamin D. However, some adults are more likely to be lacking in vitamin D than others. For example, one third of those aged 65 and over, and 94 percent of people of South Asian desent.
You are more at risk of developing vitamin D deficiency leading to osteomalacia if you:
Less commonly, vitamin D deficiency can be caused by underlying conditions such as:
Occasionally, osteomalacia can be due to a lack of phosphorus in your body. This can be caused by taking certain antacid tablets (such as aluminium hydroxide, Alu-Cap) over a long period of time, kidney disease or a rare inherited disease called hypophosphataemic rickets.
This is when the cells that lay down the minerals in your bones, in the mineralisation process, don't work properly.
Diagnosis of osteomalacia
Your GP will ask about your symptoms and carry out an examination. He or she may also ask you about your medical history.
If your GP suspects you have osteomalacia, you will be asked to take a blood test. This will measure the amount of vitamin D, calcium and phosphorous in your blood. You may also be referred to the hospital for an X-ray to check for stress fractures, especially if any parts of your body are painful or tender.
You may be referred to a specialist for treatment or monitoring, especially if there is no obvious cause for your condition, you have an underlying condition that needs further treatment or you don't respond to the treatment prescribed to you by your GP.
Treatment for osteomalacia
Osteomalacia is usually caused by a lack of vitamin D, so your GP will prescribe you daily vitamin D and calcium supplements. For some people, a yearly injection of vitamin D will be given rather than daily vitamin D supplements.
This treatment is very effective in treating osteomalacia. You may continue to have bone pain and muscle weakness for several months after you start your treatment, but this will eventually go.
You will need to continue taking vitamin D supplements for the rest of your life, otherwise your osteomalacia will come back.
It's very important that you take the correct dosage of supplements as specified by your GP. If you have too much vitamin D, you may develop vitamin D toxicity, which causes an excess of calcium in your body (hypercalcaemia). Also, recent research has shown that post-menopausal women who take vitamin D and calcium supplements are at risk of developing kidney stones. If you have any concerns, talk to your GP.
If your osteomalacia is caused by phosphorus deficiency, mineralisation defects or any other underlying conditions, you will be referred to a specialist doctor for treatment.
Prevention of osteomalacia
There are several measures you can take to prevent osteomalacia.
Eat plenty of foods rich in calcium and vitamin D.
Good sources of calcium include:
Not many foods contain enough vitamin D to give you your daily requirement, the main source is sunlight. However, it can be found in:
Most of the vitamin D you need comes from the sun. In the UK, people with light skin only need about 15 minutes of sun on their hands or face, two or three times a week during the spring and summer months, to get enough vitamin D. Those with darker skin may need longer.
However, you need to be careful as your skin can burn in the sun. It's important to keep out of the sun between 11am and 3pm, use sunscreen and keep mostly covered up.
Taking daily supplements containing 10 micrograms of vitamin D will help to prevent osteomalacia. People at risk of vitamin D deficiency (ie, over the age of 65, or of Asian, African Caribbean or Middle Eastern decent) may need a higher dose of 20 micrograms a day. You can buy vitamin D supplements from your pharmacist. Always read the patient information leaflet that comes with your supplements.
If you are pregnant or breastfeeding it's important that you get enough vitamin D to prevent your baby getting rickets. The Department of Health recommends that women who are pregnant or breastfeeding take 10 micrograms of vitamin D a day. Some families may be eligible for free vitamin D supplements from the government run Welfare Foods Scheme.