What Are Bones Made Of?

Bones have a thick outer shell and a strong inner mesh. This mesh looks like a honeycomb. It contains collagen, protein, calcium, and other minerals. There are blood vessels and bone marrow in the other spaces of the bones. Having holes in your bones does not make them weaker. As with bricks or cement blocks, holes strengthen bones.

Some of the minerals that build bones are calcium, phosphorus, magnesium, and fluoride. With osteopenia, bones do not have enough of these minerals. This is often called low mineral density. It makes the bones weak and brittle.

Low bone density can happen for several reasons, such as not getting enough vitamin D, the body not building strong bones, ongoing inflammation, or trouble absorbing nutrients. In people with cystic fibrosis, these issues can start in childhood and often become more noticeable during the teen and adult years.

With osteoporosis, the holes you normally have in your bones get too big. This is why osteoporosis means “porous bones.” Both osteopenia and osteoporosis make bones more fragile and prone to breaking or fracturing.

Since people with CF can have low bone minerals, they are at risk for osteopenia. In CF, it can happen at any age but becomes more common in the later teen and adult years. Fractures hurt. A broken rib makes it hard to breathe deep and do airway clearance. Broken bones can affect lung health.

Severe osteoporosis can keep people from getting organ transplants. Poor bone health can cause big problems after a transplant.

Screening

As part of routine CF care, CF care teams regularly check height, weight, and pubertal development to understand overall growth and health, which can influence bone strength over time. Screening for bone disease, such as osteopenia or osteoporosis, involves other tests. Some yearly lab tests screen for bone disease. For example, people with CF should be screened yearly for vitamin D levels. And if you take extra vitamin D because of low levels, lab tests will be done more often to check vitamin D levels.

You may have a dual-energy X-ray absorptiometry (DXA) scan. This checks bone mass or density and can diagnose osteoporosis. It is painless. It uses an X-ray to check bone thickness throughout the body. It can find weak bones before they break. It can predict the chance of future breaks. All people with CF should have a DXA scan by age 18. The scan is done every 1 to 5 years. If you or your child are prone to, or have, osteoporosis, the DXA scan will be done more often.