(Related Hormone: 25-hydroxy vitamin D)
Rickets is an endocrine problem in children where there is abnormal softening of the bones due to lack of minerals to strengthen it. It is also known as osteomalacia in adults. Osteomalacia literally means soft bones (from the Greek language, ‘osteo’ meaning bone and ‘malakia’ meaning softness).
What is rickets/osteomalacia?
In order for our bones to remain strong throughout our lives, they are constantly being broken down and rebuilt. The whole of our skeleton is renewed approximately every eight years. Minerals such as calcium and phosphate form part of the bone’s structure and strengthen it. This process (known as mineralisation) is aided by a hormone, 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 a 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 softening of the bones.
What causes rickets/osteomalacia?
There are several causes of this condition:
- Vitamin D deficiency –
- The commonest cause of rickets/osteomalacia is lack of vitamin D over a long period of time. Sunlight mainly regulates vitamin D production. Vitamin D is produced when skin is exposed to sunlight and the optimal timing for sun-exposure is between 10 am and 2 pm. People are therefore more likely to develop vitamin D deficiency and are at risk of developing osteomalacia if they lack exposure to sunlight, cover up extensively or wear too much sunscreen when outdoors. Also people with darker skin, for example our Indian population have skin which is less sensitive to the benefits of sunlight exposure.
- A smaller amount of vitamin D comes from diet. Foods which 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 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 kidneydisease 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.
- 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 kidneysare not able to retain phosphate which then leads to phosphate deficiency. Severe dietary calcium deficiency can cause rickets/osteomalacia.
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 moderate 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.
If osteomalacia leads to a fall in calcium levels in the blood, this can lead to tingling of the fingers and lips and cramping of hands and feet and even stridor.
In children, rickets can cause:
- Bowing of the legs
- The chest wall appearing to stick out or protrude
- 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 (waddling gait). As bones are fragile, broken bones are more common and this can happen without significant injury(fragility fractures). Rickets can also cause delayed formation of teeth and weak enamel.
How common is rickets/osteomalacia?
Vitamin D deficiency is very common in India.
People most at risk include:
- People with dark skin
- People who stay indoors, such as elderly people in nursing homes
- People who cover themselves up with a lot of clothing
- People who use a lot of sunscreen
- Vegetarians or vegans
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 (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 less than 50 known families affected worldwide.
How is rickets/osteomalacia diagnosed?
Diagnosis is made through taking a medical history and simple blood tests to check vitamin D, calcium, phosphate and parathyroid hormone levels. The doctor may also use the blood tests to check kidney and liver function. X-rays may be taken to show 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 much calcium the patient has in their bones, although this is often left until after vitamin D levels have been replaced to avoid confusion with osteoporosis, which is different from osteomalacia but low bone mineral density is seen in both.
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(swallowed or chewed), sachet or syrup.
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 orally every few weeks or through an injection(Inj.Arachitol) 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. As some of the preparations contain calcium, patients may not like the slightly chalky taste. Serious side-effects are rare if the correct dose is taken as prescribed by an endocrinologist.
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 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. Adequate exposure to sunlight is important, especially between 10am and 2pm for around 15 minutes daily.