Tuesday, June 26, 2007

DEXA Scans

Over the last decade, CF researchers and physicians have observed that as patients with CF age, their metabolic rate (i.e. how much energy the body uses) changes are disease severity increases. Malabsorption issues are closely linked with poor performance on pulmonary function tests. It is of utmost importance that CF patients and their clinics work hard to maintain adequate nutritional status.

People with cystic fibrosis, especially those who are diagnosed as having pancreatic insufficiency, have great difficulty absorbing vital minerals and nutrients from food. Doctors regularly prescribe vitamin and mineral supplements for CF patients with the expectation and hope that semi-normal levels of these can be attained in the body.

Without sufficient concentrations of certain vitamins and minerals in the body, a patient with CF may develop bone density problems. As the number of patients exhibiting weak bones has increased, there is an added emphasis being placed on the necessity of what are called DEXA scans.

DEXA (dual energy x-ray absorptiometry) scans should be performed every three years to measure bone mineral density.

The procedure of a DEXA scan is painless and simple. The patient lies on his/her back on an examination table under a scanner arm. The scanner then uses x-ray beams from two different directions to the patient’s body. The energy from the x-rays travels at a particular frequency, and is transmitted to a receiver that determines how quickly it moved through the bone. It does this by counting photons, which are energy particles. In places where the bone is denser, the x-ray beam slows down. By measuring these rates of transmission, overall bone density is calculated.

A computer takes the information about the number of photons and compares it to a normal, expected value. The result is called a “T” score. Different T scores can tell a doctor whether a patient is at risk for developing osteoporosis, or is perhaps exhibiting osteopenia.

The entire DEXA scan procedure only takes 4 minutes to scan the entire body. Since the test is performed annually, the CF team can identify problems with mineral density and work with a patient to take preventive measures to prevent bone loss. Calcium supplements with D vitamins added are commonly prescribed. Vitamin D, which is a fat soluble vitamin, is directly responsible for how much calcium comprises the bones in the body.

Many people have heard of osteoporosis, but osteopenia is not as commonly known. Osteopenia is when a person's bones are less dense than normal. Eventually it could lead to osteoporosis. Typically people who develop this condition are much older and are likely to be post-menopausal women. Bone density losses take place more frequently as people age. However, people with CF are likely to be diagnoses with osteopenia or osteoporosis at younger ages.. Without sufficient vitamin D and calcium to build strong bones, the risk of developing osteoporosis or osteopenia increases.

Other things that can help a patient safeguard his/herself against future problems with bone mineralization includes the following:

  • eat a diet rich in calcium and vitamin D
  • limit caffeine intake
  • limit alcohol consumption
  • do weight-bearing exercise like running, walking, or hiking (basically anything that forces my body to work against gravity)
  • take care of mental health issues so that they don't adversely affect physical health
  • sit in the sun for about 15 minutes per day to give the body the opportunity to make its own vitamin D

For more information please visit the following links:

Nutritional Problems in CF
Post-Transplant Osteoporosis in CF
Prepubertal Bone Mineral Accretion
Study of Benefits of Growth Hormone for CF

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