Rickets

Rickets

What causes rickets?

Initially rickets in infants and children, or brittle-bone disease and osteomalacia in teenagers and adults, was solely attributed to vitamin D deficiency. Additional research in many countries, including South Africa, has now shown that a diet lacking in calcium can also cause rickets even if the vitamin D status is adequate. Vitamin D deficiency can be caused by a lack of vitamin D in the diet, insufficient exposure to sunlight, or malabsorption of dietary vitamin D caused by other diseases and conditions that interfere with nutrient uptake, such as coeliac disease and intestinal bypass surgery. Calcium deficiency is primarily due to a diet lacking calcium-rich foods (milk and dairy products), dependence on a single staple food such as maize meal (compounds called phytates in cereals prevent the absorption of calcium) as was found in South Africa and Nigeria in young children after weaning, and in teenagers who drink large quantities of cold drinks instead of milk. Excessive excretion of calcium in the urine due to illnesses such as inherited kidney disease (hypophosphataemia, Fanconi syndrome), kidney dysfunction or kidney tumours, can also cause rickets. The latter conditions are relatively rare and most cases of rickets are linked to dietary deficiency of vitamin D and/or calcium, lack of exposure to sunlight or coeliac disease.

The following factors contribute to development of rickets/osteomalacia/brittle-bone disease

• Maternal vitamin D and/or calcium deficiency
• Diets lacking in vitamin D and/or calcium and reliance on a single staple food with a high phytate content
• Modern lifestyles, spending daylight hours indoors working, attending school, playing computer games and watching TV instead of working and playing in the sunshine. Lack of physical activity and time spent outside.
• Air pollution which limits sun exposure
• Geographic location (latitude and altitude)
• Seasons (rickets are more prevalent in spring and early summer after winter when sun exposure is limited)
• Darker skin colour
• Religions and social customs which prevent exposure of the skin to sunlight
• A family history of rickets and bone deformation
• Genetic factors that result in reduced uptake of calcium
• Coeliac disease which prevents adequate uptake of vitamin D from foods
• Kidney disease, dysfunction and tumours
• Bypass surgery that reduces vitamin D and calcium absorption

Who gets rickets and who is at risk?

Rickets is more common in children (highest prevalence 3-18 months), and in Southern Africa this condition tends to occur in infants and children who are either exclusively breast-fed by mothers deficient in vitamin D and calcium, or fed an inadequate diet or are kept indoors for long periods of time and not exposed to sunlight. The incidence is higher in the Western Cape during winter and in infants who are swaddled so comprehensively that they do not get a chance to synthesise vitamin D under the skin. Teenagers who spend most of the day in school, playing video games and watching TV thus no longer exposing their skins to sunlight, and eat diets deficient in vitamin D and calcium (drinking cold drinks instead of milk), have an increased risk of developing rickets or brittle-bone disease and stress fractures.

Pregnant and breastfeeding women who eat a diet deficient in vitamin D and calcium, and seldom expose their skins to sunlight, are at risk of developing adult rickets or osteomalacia.

Older people, especially those who are institutionalised and/or bedridden may be at risk of developing osteomalacia if their diets lack vitamin D, and/or calcium and they are not exposed to sunlight.

Patients suffering from coeliac disease or those who have undergone intestinal bypass surgery may be at risk if their condition interferes with the absorption of vitamin D from the digestive tract.

Rickets is no longer as prevalent as it was during the last century (in the early 1900s until after the First World War), when it reached epidemic proportions in malnourished populations living in areas with little sunshine. However, there has been an upsurge in the incidence of bone disease related to vitamin D and/or calcium deficiency in recent years, particularly in infants and mothers in the Middle East (Qatar, Turkey), and in infants and children in many developing countries (Ethiopia, Nigeria, Yemen and Bangladesh). In the latter countries sunlight exposure is adequate, but a monotonous cereal-based diet which lacks variety and contains few or no dairy products, is held responsible for the increase in rickets. In the latter cases provision of calcium supplements are able to cure the condition.

Symptoms and signs of rickets

Rickets causes malformed bones and teeth. In babies the skull remains soft and the bones do not close properly. The bones of the skeleton are soft and the ends of the long bones of the legs and arms are enlarged. Characteristic symptoms of rickets include bow legs, a condition called “rachitic rosary” in which knobs of bone stick out of the chest, pigeon breast (protruding breast-bone) and a curved spine. The wrists, knees and ankle joints may be enlarged.

Rickets is also associated with weak, poorly developed muscles, lack of muscle tone, a protruding tummy, and a delay in walking. Infants are often restless and irritable.

Dental caries and misshapen teeth may be linked to rickets.

How is rickets diagnosed?

Your doctor will do a physical examination to determine if the bones of the skeleton are malformed and if any of the characteristic signs of rickets or osteomalacia are present. He or she will also test your muscles to detect weakness, and will probably take a blood sample for analysis and ask for X-rays of the skeleton to be done. In rare cases, a biopsy (tissue sample for laboratory analysis) of the bone tissue may be performed.

While taking a case history, the doctor will ask you about your/your child’s diet and if you/your child are/is getting enough sun exposure.

Can rickets be prevented?

Rickets caused by dietary deficiency of vitamin D and calcium can be prevented by eating a balanced diet that includes egg yolk, oily fish and margarine that contains added vitamin D, and milk, yoghurt, maas, cottage cheese and other cheeses to provide readily available calcium. Make sure that you and your children spend some time outdoors every day, so that the body gets a chance to manufacture vitamin D under the skin when it is exposed to ultraviolet rays.

Don’t wrap up babies so tightly that they never get a chance to produce vitamin D. Pregnant and breastfeeding women and older individuals should also spend time outdoors every day, particularly in winter.

Cod liver oil tablets are a rich source of vitamin D and your doctor may prescribe them if he/she suspects that you or your children are at risk of developing a vitamin D deficiency. Always take cod liver oil tablets as prescribed and do not increase the dose, as cod liver oil also contains large quantities of vitamin A, which is stored in the human body. Excessive intake of cod liver oil can be harmful because of build-up of vitamin A in the body.

Nowadays vitamin D supplements which contain only vitamin D may be prescribed, or you may have to take a combined calcium and vitamin D supplement.

Due to the increase in rickets and brittle-bone disease, regular provision of vitamin D supplements to infants, children, teenagers, pregnant and lactating women, and the aged, is being considered. It has been suggested that healthy infants, children and adolescents should take at least 400 IU of vitamin D a day to prevent deficiency and rickets.

The question if staple foods should be fortified with vitamin D is currently under discussion in countries such as India. In Southern Africa, maize meal and wheat flour and bread, are not fortified with vitamin D at present.

How is rickets treated?

If you ( your child) have (has) been clinically diagnosed with rickets, your doctor will advise you to increase your ( your child’s) vitamin D and calcium intake by eating a healthy, balanced diet containing plenty of milk, cheese, dairy products, egg yolk and fish. Make sure that the margarine you are using contains vitamin D. Cod liver oil tablets, vitamin D supplements and combination supplements which contain both vitamin D and calcium may be prescribed to supplement vitamin D and calcium intake. Calcium supplements alone may be prescribed if your (your child’s) vitamin D status is adequate, but you (your child) have (has) a calcium deficiency.

Also, spend about half an hour outside the house every day to expose your body to the ultraviolet rays of the sun. (However, remember to avoid the sun between 10 a.m. and 3 p.m. during the Southern Africa summer, especially if you are fair-skinned, because of the associated risk of skin cancer).

Research in India and the USA has indicated that people with dark skins are more susceptible to vitamin D deficiency and that such individuals should spend more time in the sun.

What is the outcome of rickets?

If treated in time, the bone and tooth malformations in infants can to a great extent be reversed. In adults, exposure to sunlight and provision of adequate nutrition, including vitamin D and calcium supplements, should also reverse skeletal malformation. Dental damage may not respond to treatment and affected teeth may have to be extracted.

What is the outcome of rickets?

If treated in time, the bone and tooth malformations in infants can to a great extent be reversed. In adults, exposure to sunlight and provision of adequate nutrition, including vitamin D and calcium supplements, should also reverse skeletal malformation. Dental damage may not respond to treatment and affected teeth may have to be extracted.

When to call the doctor

Consult your doctor if:

• You suspect that your baby’s bones and teeth are malformed or not developing properly.
• Your child has any of the symptoms listed above.
• You suspect that you and/or your child eat a diet that does not contain sufficient vitamin D or calcium.
• You and/or your children never go out of doors and you notice any bone or muscle changes.
• You are bedridden, suffer from coeliac disease or have had intestinal bypass surgery.

Written by Dr I.V. van Heerden, D.Sc.

References

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