Alternative names for rickets/osteomalacia

Osteomalacia literally means soft bones, from the Greek language, ‘osteo’ meaning bone and ‘malakia’ meaning softness.

What is rickets/osteomalacia?

Coloured X-ray of the weakened bones and bowed legs of a child suffering from rickets.

In order for our bones to remain strong throughout our lives, they are constantly being broken down and rebuilt to maintain their normal structure. The whole of our skeleton is renewed approximately every eight years in adulthood, and much more frequently in children. Minerals such as calcium and phosphate form part of the bone’s structure to strengthen it and protect it from damage. This process (known as mineralisation) is aided by vitamin D, which also helps the body absorb enough calcium from the diet to provide the body with the building blocks to build bones. If a person lacks calcium or vitamin D, this will result in the softening of the bones. In adults, this condition is known as osteomalacia. In children, the same condition is called rickets. As the bones are growing, children with rickets end up with bony deformities because of this softening of the bones.

What causes rickets/osteomalacia?

There are several causes of this condition:

1. Vitamin D deficiency –
   • The commonest cause of rickets/osteomalacia is lack of vitamin D over a long period of time. It is mainly sunlight that controls vitamin D production from cholesterol in the skin. Vitamin D is produced when skin is exposed to sunlight, but, in countries like the UK, the sunlight is only strong enough to do this between the months of April and October. People are therefore more likely to develop vitamin D deficiency and are at risk of developing rickets/osteomalacia, especially if they lack exposure to sunlight, cover up extensively or wear too much sunscreen when outdoors. Also, people with darker skin, for example Asian or Afro-Caribbean people, have skin that is less sensitive to the benefits of sunlight exposure.
   • A smaller amount of vitamin D comes from diet. Foods that are rich in vitamin D include oily fish (such as salmon), breakfast cereals, margarine and eggs. People with a vegetarian or vegan diet are at risk of a vitamin D deficiency or developing rickets/osteomalacia. Vitamin D supplements are widely available and are effective for supplementing dietary vitamin D. 
   • Vitamin D deficiency can also result from the body not absorbing nutrients properly (malabsorption) due to conditions such as coeliac disease, stomach and abdominal surgery, Crohn’s disease and chronic
   • People with chronic kidney disease or liver disease such as cirrhosis, are also at risk of vitamin D deficiency.
   • Babies depend on their mothers to provide them with adequate vitamin D. A lack of vitamin D in pregnant or breastfeeding women can lead to rickets in the child.
2. Phosphate and calcium deficiency– less commonly, osteomalacia/rickets can be caused by phosphate or calcium deficiency. In certain rare conditions, some of which are inherited, the kidneys are not able to retain phosphate, which then leads to phosphate deficiency. Severe dietary calcium deficiency can cause rickets/osteomalacia, although it is rarely seen in the UK.

What are the signs and symptoms of rickets/osteomalacia?

Symptoms of osteomalacia can be vague with the person complaining of not feeling well with general aches and pains. Widespread bone pain, especially in the hips and lower back, can occur. The bones can be unnaturally tender even with minimal pressure. In later stages, the person may develop muscle weakness, particularly of the thighs which causes difficulty in getting up from a sitting position and walking up stairs.

In children, rickets can cause:

• bowing of the legs
• the chest wall appearing to stick out
• soft skull bones
• curvature of the spine
• short stature.

Children may have bone pain and weak muscles leading to delayed walking or a change in the way they walk (gait). This is sometimes called a waddling gait. As bones are fragile, broken bones are more common and this can happen without significant injury. Rickets can also cause delayed formation of teeth and weakening of the enamel.

Severe vitamin D deficiency can also lead to a fall in calcium levels (hypocalcaemia), which can cause numbness or tingling around the mouth and in the fingers and toes.

How common is rickets/osteomalacia?

In the UK, about 1.6% of the population has rickets, mainly in the ethnic minorities such as people from India and Pakistan. About 50% of people in the UK have low levels of vitamin D, which is less serious.

Is rickets/osteomalacia inherited?

Usually it is not inherited. Rarely, rickets can run in families where there is a problem in vitamin D activation (vitamin D dependent rickets type 1). Another rarer type of inherited rickets is hereditary vitamin D resistant rickets (previously known as vitamin D dependent rickets type 2) where there is a problem with the body not responding to the actions of vitamin D. This is very rare, with fewer than 50 known families affected worldwide. Another very rare inherited disease is X-linked hypophosphataemic rickets, where people have very low levels of phosphate in the blood due to a subtle, genetically determined, kidney defect.

How is rickets/osteomalacia diagnosed?  

Diagnosis is made through taking a medical history and simple blood tests to check vitamin D, calcium, phosphate and sometimes parathyroid hormone levels. The doctor may also use the blood tests to check kidney and liver function. X-rays may be taken to look for some characteristic bone changes although this is not always needed to make the diagnosis. The doctor may also arrange a dual energy X-ray absorptiometry (DEXA bone scan) to check how  strong the bones are, although this is often left until after vitamin D levels have been replaced to avoid confusion with osteoporosis, which is different from osteomalacia.

How is rickets/osteomalacia treated?

As the majority of cases are due to vitamin D deficiency, treatment is with vitamin D replacement. This can be in the form of tablets or liquid medication.

However, if the patient is severely deficient in vitamin D or has very severe symptoms, larger doses of vitamin D may be given. This can be taken either as tablets every few weeks or through an injection given into the muscle every few months. Injections may also be considered for people who have a problem with absorbing the medication.

Are there any side-effects to the treatment?

Patients generally cope well with treatment. Serious side-effects are rare if the correct dose is taken.

What are the longer-term implications of rickets/osteomalacia?

If rickets is not identified and treated before the bones stop growing, a child may be left with some deformities, often bowing of bones in the legs. In adults, untreated osteomalacia can cause an increased chance of breaking bones and a low level of calcium in bones, particularly in old age.

A good diet is important in order to prevent rickets/osteomalacia. Calcium can be found in cow’s milk and dairy products. Oily fish such as sardines, mackerel and salmon are good dietary sources of vitamin D. In the UK, foods such as breakfast cereals and margarine are fortified with vitamin D. Adequate exposure to sunlight is important, especially between April and October for around 15 minutes daily.