Rickets / Bow bend legs / Vitamin D deficiency

What is rickets and what causes it?

Rickets is a condition that affects growing bones - so it only occurs in children. (Children in this article includes babies and teenagers.) Bones are made strong by a mineral which contains calcium. 

When a child has rickets, there is not enough "mineral" in the bones. This makes the bones softer and weaker, and also causes weak muscles.

The main cause of rickets is lack of vitamin D. It is vitamin D which regulates the bone building process and the way the body handles calcium.

Lack of vitamin D is caused by problems with our diet and lifestyle. 

Most of our vitamin D is made by the body itself when sunshine shines directly onto skin. People can lack vitamin D if they spend too much time indoors, or cover up when outside. The problem is worse in cold climates, and for people with dark skin when the effect of the sun on the skin is less. 

Some vitamin D is obtained from certain foods: liver, oily fish (such as sardines, herring, tuna, salmon, and mackerel), and egg yolk. A diet low in these foods will also contribute to a lack of vitamin D - 

But the main cause of the problem is lack of sunlight on the skin.

Babies get vitamin D from their mothers while in the womb, and then from milk until they are weaned. If a pregnant or breastfeeding woman is lacking in vitamin D, the baby will also have low vitamin D levels. This is a common reason why babies get rickets, and the problem can occur both in the newborn period and later.

Another possible cause of rickets is a very severe lack of calcium in the diet. This is unlikely in western countries, but can occur with very restricted diets and in developing countries.

Rickets can be caused by other medical conditions which affect the way the body processes vitamin D or calcium. Some examples are:

• • Problems affecting the gut such as coeliac disease, Crohn's disease or malabsorption.

  • Some types of liver or kidney disease (because the liver and kidneys are involved in processing vitamin D).

  • Medicines which interfere with vitamin D: carbamazepine, phenytoin, primidone and barbiturates.

  • A few rare conditions, including some inherited ones, which affect the way the body uses vitamin D and calcium.

How common is rickets?

We don't know how common rickets is, but recently it has been recognised that rickets does affect many children in the UK. Some recent research suggests that rickets affects something like 1 in 1000 children, and is much more likely in children of South Asian or Afro-Caribbean origin. Other research gives higher figures for rickets, about 1 in 100 children in ethnic minority groups. In large cities in the UK, perhaps 20 children each year would attend a hospital clinic with a diagnosis of rickets.

Vitamin D deficiency, which makes children vulnerable to rickets, is very common and probably affects between 4 and 7 in 10 children in the UK. See separate leaflet on 'Vitamin D Deficiency'.

Who gets rickets?

Children who lack vitamin D for long periods may get rickets. Vitamin D deficiency is more likely to occur in the following situations:

• • Breastfed babies whose mothers lack vitamin D, or breastfed babies where weaning is delayed - if they are not taking vitamin drops. (These babies do not need to stop breastfeeding, they can have breast milk plus vitamin D supplements.)

  • Children who get very little sun on their skin such as those who are stay indoors a lot, or who cover up when outside.

  • Children with medical conditions which affect the way the body handles vitamin D, as listed above under causes.

  • Children with dark skins or of South Asian origin.

  • Children with a family history of vitamin D deficiency.

What are the symptoms of rickets?

Many children have no symptoms, or only vague ones such as tiredness or aches. Other symptoms may be:

• • Bone pains, often in the legs.

  • Muscle pains or muscle weakness.

  • Soft skull or leg bones. This can make the legs look curved or bow-legged.

  • Poor growth, or teeth which are delayed or weak.

  • When rickets if very severe, it can cause low levels of calcium in the blood. This can lead to muscle spasms (cramps), seizures and breathing difficulties. These need urgent hospital treatment.

How is rickets diagnosed?

It may be suspected from the child's medical history, symptoms, or lifestyle. Blood can be tested for vitamin D and calcium levels. Also, blood tests for liver function may show changes linked to rickets. A bone x-ray (usually of the wrist bones) is often done. This can show changes due to rickets (and needs only a very small amount of x-rays).

Usually, blood tests plus a bone x-ray is enough to make the diagnosis. Extra tests may be needed if the reason why the child has rickets is in doubt, or if the child could have another medical condition which may be contributing to the rickets.

How is rickets treated?

Treatment is to take vitamin D supplements. This is generally taken as a form of vitamin D called ergocalciferol or calciferol. (There are other types of vitamin D which are used in certain cases.) The vitamin D is given in high doses, in order to improve the rickets quickly.

Vitamin D can be taken as liquids, tablets or injections. The liquids/tablets can be taken on a daily, weekly or monthly basis, depending on the dose needed and on which option is preferred. If injections are used, they are NOT needed very often. For example, the first two doses could be given a month apart, followed by a repeat injection every six months.

If lack of calcium is part of the problem, calcium supplements can also be taken. These can be liquids or tablets. 

Are there any side effects of treatment?

It is very unusual to get side effects from vitamin D or calcium if taken in the correct dose.

Doses of vitamin D or calcium which are too high can raise calcium levels in the blood. This would cause symptoms such as thirst, passing a lot of urine, reduced appetite, nausea or vomiting, dizziness, and headaches. If your child has these symptoms, see a doctor immediately so that their calcium level can be checked by a blood test.

Some guidelines advise that children taking high vitamin D doses should have their calcium levels checked regularly during the first few weeks of treatment. In practice, this is not usually done unless there are symptoms of high calcium as described above.

Are there any complications of rickets?

Rickets causes softening of the bones, which can be cured by treatment. However, until treated, the bones are more prone to fractures. Severe and prolonged rickets, if treated very late, can cause bone deformities such as bow-legs.

Rickets occasionally causes low levels of calcium in the blood. If severe, low calcium can lead to muscle spasms (cramps), seizures or breathing difficulties. These problems can be treated but need hospital admission. Very rarely, severe rickets has been reported to cause heart muscle weakness, which was cured by vitamin D treatment.

What is the outlook?

If treated promptly, the outlook is very good. Most cases of rickets can be cured by vitamin D treatment. If rickets is untreated for a long time, there is a possibility that bone deformities could result. If these are a problem, they might need surgery.

With prolonged or untreated rickets, the risk of getting osteoporosis (bone thinning and fractures in old age) may be increased. It is also possible that the risk of getting other diseases might be increased. This is because vitamin D is thought to help in preventing some conditions such as diabetes, heart disease and cancer.

How can rickets be prevented?

Babies

All breastfed babies should be given vitamin drops such as Abidec or Dalivit.(Babies fed by formula baby milk do not need vitamin drops, as this milk already contains vitamin D.) Toddlers who are weaned on to ordinary milk should have supplements, as ordinary milk contains very little vitamin D.

Pregnant and breastfeeding women

If you are pregnant or breastfeeding you should take vitamin D supplements, both for your own health and to help prevent rickets in your baby. 400 units (10 micrograms) daily of vitamin D is recommended for all pregnant and breastfeeding women. This can be either a calcium/vitamin D tablet, or as a multivitamin tablet labelled as suitable for use in pregnancy. Some experts think that women who get very little sunshine need a higher preventative dose such as 800 units (20 micrograms) daily. Pregnant women can get free prescriptions and vitamins.

Note: if you are pregnant, do not take supplements containing large amounts of vitamin A, as too much can harm the baby. Supplements labelled as suitable for pregnancy are safe to use. Also, do not eat liver which contains large amounts of vitamin A. Vitamin A can be taken if you are breastfeeding.

Lifestyle changes to prevent rickets

Vitamin D deficiency can also be prevented by lifestyle changes (to get more sunshine and improve the diet). However, many people find it hard to change their children's lifestyle, in which case supplements are advised.

Foods containing good amounts of vitamin D are: liver, some fish (mainly oily fish such as herring, sardines, pilchards, trout, salmon, tuna and mackerel), egg yolk, and 'fortified' foods (which have vitamin D added) such as some margarines and breakfast cereals.

Sunshine: 15 minutes three times weekly from April to September, with hands, arms and face uncovered, is said to be enough for fair-skinned people. Darker-skinned people will need more sunshine (we don't know how much more). However, in winter in cold climates, there is not enough sunshine to maintain vitamin D levels.

Calcium deficiency can be prevented by eating a reasonable amount of dairy food (milk, cheese and yoghurt). If the child has special dietary needs, such as not eating dairy products, a dietician is usually asked to advise.

Some special circumstances

Children with certain medical conditions which make them prone to vitamin D deficiency will need extra vitamin D. The dose needed will depend on which medical condition it is. See above in 'what causes vitamin D deficiency?' for a list of these conditions, and discuss vitamin D with your doctor.

If you have been treated for rickets

Once rickets has been diagnosed and treated, prevention will be needed so that rickets does not recur in the future. Most children diagnosed with rickets need to take vitamin D supplements long term. These can be either vitamin drops/tablets taken daily, or stronger vitamin D medicines or injections taken at longer intervals such as monthly or six-monthly. If your child has had rickets, it would be sensible to discuss prevention with your doctor.

References

• • Drug and Therapeutics Bulletin; Primary vitamin D deficiency in children. February 2006 44: 12-16.; (Requires a subscription)

  • Pettifor JM; Nutritional rickets: deficiency of vitamin D, calcium, or both? Am J Clin Nutr. 2004 Dec;80(6 Suppl):1725S-9S. [abstract]

  • Holick MF; Vitamin D deficiency. N Engl J Med. 2007 Jul 19;357(3):266-81.

  • Scientific Advisory Committe on Nutrition; Update on Vitamin D, February 2007.

  • Rickets (GPN); General Practice Notebook

  • https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6224631/

  • https://akvasurgical.com/eight-plate/