Vitamin D deficiency rickets, a disorder that causes soft and weak bones and often results in bone deformities, such as bowed legs or knocked knees.

Mikayla's story: Overcoming challenges to lead an active, healthy life

Most kids don't think twice about taking part in activities such as jumping rope and climbing trees, but when 10-year-old Mikayla was younger, she had to be extra careful when doing even the simplest activities. That's because at just 18 months old, Mikayla was diagnosed with a condition that put her at serious risk for injury.

When Mikayla's mom started to notice that her daughter was having trouble controlling her left leg when she tried to walk, she turned to doctors at Nationwide Children's Hospital to help find out what was wrong.

A small walking problem turned into much more when doctors found more than 30 fractures in Mikayla's left leg. After several blood tests and X-rays, doctors diagnosed Mikayla with vitamin D deficiency rickets, a disorder that causes soft and weak bones and often results in bone deformities, such as bowed legs or knocked knees.

Rickets is caused by severe vitamin D deficiency, a nutrient that is essential for strong bones because it helps the body absorb calcium. It was a common ailment in toddlers or young children in the past before the availability of vitamin D-fortified milk. But rickets has never been eradicated and physicians at Nationwide Children's continue to diagnose many young patients with rickets.

Children become at risk for vitamin D deficiency rickets when they do not get enough vitamin D in their diets. For toddlers, this typically occurs when they do not drink enough vitamin D-fortified milk, and in infants when they don't get enough vitamin D supplements while breastfeeding. Human breast milk lacks sufficient vitamin D. Also, inadequate exposure to sunlight can lead to vitamin D deficiency rickets. Since very few foods naturally contain vitamin D, most people get vitamin D naturally from exposure to sunlight.

As Mikayla got older, she began learning different ways of increasing her vitamin D levels from her doctors at Nationwide Children's. From playing outside in the sun and learning to be careful when performing certain activities, Mikayla was on her way to building strong and healthy bones.

Now you can find Mikayla swimming, jumping rope and bowling--a few activities that, before being diagnosed with rickets, she was unable to do.

PEDIATRIC ADVANCEMENTS: Vitamin D critical for strong, healthy bones

While severe vitamin D deficiency causes rickets, a less severe form of vitamin D deficiency, called vitamin D insufficiency, can also have negative effects on bone health, causing low bone mass or low bone density. It also may worsen pre-existing conditions, such as underlying metabolic bone disease (including brittle bone disease or steroids-induced osteoporosis).

A study conducted by physicians and researchers at Nationwide Children's Hospital is the first study to investigate vitamin D insufficiency in pediatric patients with low bone density. Researchers found that vitamin D insufficiency is very prevalent, seen in up to 80 percent of pediatric patients with low bone density and/or with multiple fractures.

As a result, pediatricians must be on the lookout for vitamin D insufficiency when caring for patients with chronic medical conditions. Certain illnesses can result in poor absorption of vitamin D and some medications can interfere with the way the body processes vitamin D. These patients often exhibit muscle weakness or low bone density, both of which are signs of vitamin D insufficiency.

"It is extremely important to monitor vitamin D levels in all patients with a history of multiple fractures or low bone density," said Sasigarn Bowden, MD, a pediatric endocrinologist in the Metabolic Bone Clinic at Nationwide Children's Hospital and the study's lead author. "If the levels are low, a vitamin D supplement should be provided."