Disorders due to lack of vitamin D, resulting in weak, soft bones that become distorted or fracture easily
- Osteomalacia develops in adults; rickets develops in children
- In some cases, the cause is inherited
- Minimal exposure to sunlight and vegan or fat-free diets are risk factors
- Gender is not a significant factor
The minerals calcium and phosphate give bone its strength and density. A deficiency of vitamin D results in poor absorption of calcium from the diet, leading to weak and soft bones that are easily deformed or fractured. In adults, the condition is called osteomalacia; in children, it is known as rickets.
What are the causes?
Healthy people obtain the vitamin D they need partly from their diet (from eggs, fish, fortified margarine, milk, and some cereals) and partly from vitamin D production in the skin on exposure to sunlight. A deficiency of vitamin D, therefore, is most common in people who eat a restricted diet and receive little direct sunlight. In tropical countries, vitamin D deficiency is almost unknown, except in women who are required to cover their entire bodies. At higher latitudes, deficiency may occur in elderly, housebound people.
Some people cannot absorb vitamin D from food due to intestinal surgery or coeliac disease. Less commonly, osteomalacia and rickets may be caused by inherited disorders of vitamin D metabolism or chronic kidney failure. In rare cases, drugs used to treat epilepsy (see Anticonvulsant drugs) interfere with vitamin D metabolism and cause osteomalacia or rickets.
What are the symptoms?
The symptoms of osteomalacia develop over months or years and may include:
Painful, tender bones, most often the ribs, hips, and bones of the legs.
Difficulty in climbing stairs or in getting up from a squatting position.
Bone fractures after a minor injury.
A child with rickets may experience similar symptoms, and may also have:
Swelling and tenderness at the growing ends of the bones.
Prominence of the ribs where they join the breastbone.
Left untreated, bow legs or knock-knees may develop in affected children.
What might be done?
Your doctor may suspect osteomalacia or rickets from your symptoms and a physical examination. He or she may arrange for blood tests to check for low levels of calcium, phosphate, and vitamin D. A bone biopsy, in which a bone sample is taken for analysis, or X-rays can confirm the diagnosis.
If you have a vitamin D deficiency, you should eat foods rich in vitamin D (see A healthy diet) and increase your exposure to sunlight. If you have a disorder that prevents absorption of the vitamin from food, you may need to have vitamin D injections (see Vitamins). Calcium supplements (see Minerals) may also be required.
After treatment, most people make a full recovery, although deformities that occur in childhood may be permanent.
From the 2010 revision of the Complete Home Medical Guide © Dorling Kindersley Limited.
The subjects, conditions and treatments covered in this encyclopaedia are for information only and may not be covered by your insurance product should you make a claim.