Rickets is the softening and weakening of bones in children, usually because of an extreme and prolonged vitamin D deficiency.

Vitamin D is essential in promoting absorption of calcium and phosphorus from the gastrointestinal tract, which your child needs to build strong bones. A deficiency of vitamin D makes it difficult to maintain proper calcium and phosphorus levels in bones.

If a vitamin D or calcium deficiency causes rickets, adding vitamin D or calcium to the diet generally corrects any resulting bone problems for your child. Rickets due to a genetic condition may require additional medications or other treatment. Some skeletal deformities caused by rickets may need corrective surgery.

Vitamin D deficiency begins slowly before physical signs and symptoms of rickets appear. When rickets signs and symptoms develop, they may include:

• Skeletal deformities. These include bowed legs, abnormal curvature of the spine, pelvic deformities and breastbone projection in the chest.
• Fragile bones. Children with rickets are more prone to bone fractures.
• Impaired growth. Delayed growth in height or limbs may be a result of rickets.
• Dental problems. These include defects in tooth structure, increased chance of cavities, poor enamel and delayed formation of teeth.
• Bone pain. This includes dull, aching pain or tenderness in the spine, pelvis and legs.
• Muscle weakness. Decreased muscle tone may make movement uncomfortable.

When to see a doctor
If your child exhibits signs or symptoms of rickets, such as bone pain, muscle weakness or obvious skeletal problems, make an appointment with your child's doctor.

Vitamin D acts as a hormone to regulate calcium and phosphorus levels in your bones. If you don't get enough vitamin D, your body won't absorb calcium and phosphorus properly. When your body senses the imbalance of calcium and phosphorus in your bloodstream, it reacts by taking calcium and phosphorus from your bones to raise blood levels to where they need to be. This softens or weakens the bone structure, which can result in skeletal deformities, such as bowlegs or improper curvature of the spine. Osteomalacia is the adult version of rickets.

You absorb vitamin D from two sources:

• Sunlight. Your skin produces vitamin D when it's exposed to sunlight.
• Food. Your intestines absorb vitamin D that's found naturally in the foods you eat, or added to it during processing, or from supplements or multivitamins you may take.

Rickets can also be caused by conditions that impair vitamin D absorption, such as the surgical removal of all or part of the stomach (gastrectomy) and celiac disease, in which the small intestine doesn't absorb certain nutrients from food. Additionally, conditions that impair the absorption of any fat soluble vitamin, which includes A, D, E and K, increases the risk of rickets.

Other causes of rickets include:

• Hereditary rickets (X-linked hypophosphatemia), an inherited form of rickets caused by the inability of the kidneys to retain phosphorus, or a complication of renal tubular acidosis, a condition in which your kidneys are unable to excrete acids into urine
• Lack of exposure to sunlight, which stimulates the body to make vitamin D

Children 3 to 36 months old are most at risk of rickets because they're growing rapidly, and vitamin D, calcium and phosphorus play a major role in the growth process.

Other risk factors for rickets include:

• Lack of vitamin D. Breast-fed infants who don't receive supplemental vitamin D are at increased risk of developing rickets because although vitamin D does cross from mother to baby in the breast milk, it's not enough to prevent a deficiency. While exposure to sunlight could produce the necessary amounts of vitamin D, sunburn and skin cancer are real dangers. Sunscreens, which are used to protect against these dangers, can decrease vitamin D production by blocking the sun's ultraviolet rays.
• Lack of calcium and phosphorus. Children who don't get enough calcium and phosphorus in their diets are at increased risk of rickets.

While easily treated once it's diagnosed, rickets has a severe list of complications if left untreated. Untreated vitamin D deficiency rickets may lead to:

• Delays in your child's motor skills development
• Failure to grow and develop normally
• Skeletal deformities
• Chronic growth problems that can result in short stature
• Seizures
• Dental defects

You're likely to start by first seeing your family doctor or a pediatrician. It's a good idea to be well prepared for your appointment. Here's some information to help you get ready for your child's appointment, and what to expect from your child's doctor.

What you can do

• Write down any symptoms your child is experiencing, including any that may seem unrelated to the reason for which you scheduled the appointment.
• Make a list of all medications, as well as any vitamins or supplements, that your child is taking.
• Write down questions any questions you have for your child's doctor.

For rickets, some basic questions to ask your doctor include:

• What is the most likely cause of my child's symptoms?
• Are there any other possible causes for my child's symptoms?
• What kinds of tests does my child need?
• How is the type of rickets my child has treated?
• How can I prevent this from happening again?
• Are there any brochures or other printed material that I can take home with me? What Web sites do you recommend visiting?

In addition to the questions that you've prepared to ask your doctor, don't hesitate to ask questions during your appointment at any time that you don't understand something.

What to expect from your doctor
Your child's doctor is likely to ask you a number of questions. Being ready to answer them may reserve time to go over any points you want to spend more time on. Your child's doctor may ask:

• When did your child first begin experiencing symptoms?
• How much milk does your child consume daily? What about other dairy products?
• How much time does your child spend outdoors? Does he or she regularly wear sunscreen?

What you can do in the meantime
Before your appointment, it's a good idea to track your child's diet so that you can better assess whether he or she is getting enough vitamin D, and other nutrients.

Your doctor or your child's doctor may diagnose rickets by:

• Physical examination. Your doctor will check if the pain or tenderness is coming directly from the bones, instead of the joints and muscles surrounding them.
• Blood tests. These measure calcium and phosphorus levels to see if they're normal.
• X-rays. Your doctor may take images of affected bones to look for softening or weakness.
• Medical history. Kidney problems, celiac disease or diagnosis of a sibling with rickets may help lead your doctor to a rickets diagnosis.

The aim of treatment for rickets is to solve the underlying disorder. If deficiencies in vitamin D, calcium or phosphorus are at fault, replacing vitamin D and those minerals generally eliminates the signs and symptoms of rickets, such as bone tenderness and muscle weakness. Improvement generally occurs within three months.

Your doctor may prescribe a vitamin D supplement or ask you to increase your intake of vitamin D-fortified foods, including fortified breakfast cereal, orange juice, fish and processed milk.

Getting a sufficient intake of calcium is crucial to maintaining healthy bones. Your doctor can suggest an appropriate level of calcium intake depending on your age and whether you have absorption problems. The combination of increased vitamin D intake with calcium may be enough to eliminate the effects of rickets entirely.

Treating complications
For some cases of bowlegs or spinal deformities, your doctor may suggest special bracing to position your child's body appropriately as the bones grow. More severe skeletal deformities may require surgery.

Although most adolescents and adults receive much of their necessary vitamin D from exposure to sunlight, infants and young children need to avoid direct sun entirely or be especially careful by always wearing sunscreen.

Vitamin D supplements
In light of these factors, and because human milk contains only a small amount of vitamin D, the American Academy of Pediatrics (AAP) recommends that all breast-fed infants receive 400 international units (IU) of oral vitamin D daily beginning during the first two months of life and continuing until the daily consumption of vitamin D-fortified formula or milk is two to three glasses, or 500 milliliters (mL). AAP also recommends that all children and adolescents should receive 400 IU a day of vitamin D.

Vitamin D supplements for infants generally come in droplet form. Use only supplements that contain up to 400 IU of vitamin D per mL or tablet. Avoid supplements containing a higher concentration of vitamin D (some forms come in levels of up to 8,000 IU/mL), because they're unsafe for children.

For adults, the Institute of Medicine (IOM) recommends that adults up to age 50 consume 200 IU daily. For people between ages 50 and 70, the IOM recommends 400 IU every day, and people over age 70 are advised to consume 600 IU daily.

Getting enough calcium
Calcium and phosphorus consumption are also important for bone formation in childhood. Breast milk is a good source of calcium, as are most commercially available formulas.

Recommended daily intake of calcium is as follows (serving sizes vary with age):

• 1 to 3 years of age. 500 milligrams (mg) (two servings of dairy products a day)
• 4 to 8 years of age. 800 mg (two to three servings of dairy products a day)
• 9 to 18 years of age. 1,300 mg (four servings of dairy products a day)
• 19 to 50 years of age. 1,000 mg a day (three servings of dairy products a day)
• Older than 50. 1,200 mg a day (nearly four servings of dairy products daily)

Milk and dairy products are common sources of calcium. Other sources of calcium include leafy green vegetables (for example, spinach), fortified orange juices, fortified breakfast cereals and calcium supplements.