The Bones

You may have heard members of your CF team talk to you about your bone health. Bone mineral density is an area of concern for someone with cystic fibrosis because low bone density is found in 40-70% of adults with CF and it is something that should be monitored regularly. If you have CF, you are at risk for developing osteopenia or osteoporosis (thinning of the bones) which can lead to bone fractures, bone deformities, and bone pain. There are many reasons why this may happen including malnutrition, vitamin deficiencies, chronic inflammation, low body weight, low sex hormones, and steroid use. In your yearly visit, you will be asked to have a bone mineral density scan called a DEXA (dual energy x-ray absorptiometry) scan to check your bones. As well, we do blood work to look for any possible cause for low bone density that may be corrected with medication.

Studies have shown that, on average, CF patients have 10% lower bone mineral density compared to other people of the same age and height. Because individuals with CF are living longer now, this condition has become more relevant, as it tends to manifest later in life. Also, physicians are more aware of osteoporosis in CF patients and are looking for this condition more frequently than they were before. Idividuals with CF with thin bones have a much higher risk of breaking bones. Staying active with regular exercise not only helps improve your lung function, it also improves your bone density. The more force you apply to the bones, the stronger they become. Also, it is important to take vitamins, especially Vitamin D and calcium (in foods or supplements), to ensure adequate blood levels so that your body has the building blocks necessary to lay down new bone.

Vitamin D is a fat-soluble vitamin that influences many cells within the body. The majority of vitamin D is made in the skin after exposure to sunlight. There are very few natural dietary sources of vitamin D with the exception of fish liver oils. Because of this and the fact that in Canada, vitamin D production in the skin is minimal during the winter months, milk and baby cereal/formula is fortified with vitamin D in order to maintain vitamin D stores. One cup of milk provides you with approximately 100 IU of vitamin D. Vitamin D is necessary for maximal calcium absorption in the gastrointestinal tract. Calcium is essential for adequate bone development and strength. Although vitamin D is required to maintain bone health there is literature to suggest that vitamin D plays a role in other bodily functions as well. Large studies show that children who receive vitamin D supplementation as babies have a lower risk of developing diabetes later in life. Furthermore, individuals who live closer to the equator (thus being exposed to more sunlight) have a reduced risk of developing multiple sclerosis, raising the possibility that vitamin D may influence the development of this condition. From a pulmonary point of view, there have been two published studies suggesting that dietary vitamin D as well as blood vitamin D levels may be associated with lung function. So there are several reasons why ensuring an adequate vitamin D level is an important goal to achieve. To learn more about the benefits of Vitamin D, download this handout.

What Happens If I Don’t Get Enough Vitamin D?

Vitamin D deficiency is common not only in cystic fibrosis but also in the general population. Given the fact that individuals with CF have fat malabsorption, they are at higher risk for vitamin D deficiency (vitamin D dissolves in fat). Furthermore, many individuals with CF have low bone mineral density or “thin bones” so normalizing blood levels of vitamin D may be even more important in CF to optimize bone health. The normal range for blood vitamin D levels varies but most literature suggests that the optimal level is around 75-100 nmol/L in the bloodstream. Using this cut-off, the vast majority of individuals with CF are considered vitamin D deficient. As part of your yearly bloodwork, we measure your vitamin D level in your blood.

People with cystic fibrosis are at increased risk of bone disease, specifically low bone mineral density. After transplant, bone health continues to be very important. Steroids can thin your bones further and increase your risk for fractures. Often after transplant people may be started on medication to help preserve their bones.

In order to maintain a healthy bone status it is important to:

  • Maintain a healthy weight
  • Take recommended amounts of calcium and vitamin D
  • Include weight-bearing exercise in your daily activity regimen

Talk to your dietitian to learn about the recommended amounts vitamins and minerals.