Over the years our bones begin to lose density. This loss puts us at greater risk for bone fractures, which can have significant impact on mobility, activity levels, and overall health. Bone density scans are a vital tool for diagnosing bone loss and assessing patients’ risk of bone fractures.
Who Needs a Bone Density Scan?
Bone loss has many causes, although the most common are aging and osteoporosis. Experts recommend bone density scans for the following patients:
- Post-menopausal women who don’t take estrogen; have a family history of bone fractures; are over 5”7’; weigh less than 125 pounds; have had a previous fracture; or smoke.
- Any patient who has had a bone fracture after only a relatively minor injury or trauma
- Patients who use medications that cause bone loss. This includes corticosteroids, some barbiturates, and many anti-seizure medications.
- People with kidney disease, liver disease, Type 1 diabetes, or thyroid/parathyroid conditions
- Anyone with a family history of osteoporosis
Doctors generally recommend that these patients get a bone density scan every two years. However, those who take high doses of medication that cause bone loss may need follow-up scans after six months.
Benefits of Regular Bone Density Scans
A bone density scan helps doctors assess patients’ levels of bone loss and risk of fracture. In many cases, patients who are diagnosed early can begin a regimen of exercise and sometimes medication. This treatment plan can actually halt—and sometimes reverse—bone density loss.
Meanwhile, a bone density scan is a completely non-invasive procedure that involves only an extremely low dose of radiation. The dose of radiation used for a bone density scan is less than 10% of the dose administered during a standard chest x-ray, and significantly lower than daily levels of natural radiation exposure. The procedure can be completed on an outpatient basis.
How They Work
The most reliable tool for measuring bone density is a DXA scan. DXA stands for dual-energy x-ray absorbitrometry, which is an enhanced version of the same x-ray technology that doctors have been using for decades. DXA scanners have set the standard for accuracy and precision in measuring bone loss, which is why Central Florida Regional Hospital recently added the scanner to its Diagnostic Imaging department.
During a DXA scan, a reading is usually taken either at the spine or at the hip. The body is exposed to a very low level of ionizing radiation, which creates an image of the bone. The technician reads the scan and comes up with two numbers:
- The t-score, which compares the patient’s bone loss to that of an average 30-year-old adult. That average represents the bone mass of someone who has peak bone density. The t-score helps the doctor estimate a rate of bone loss.
- The z-score, which compares the patient’s bone loss to that of other patients the same age. This number allows doctors to determine whether a patient’s bone loss is markedly accelerated, compared to other patients who would be expected to have consistent bone mass.
Depending on the results of the scan and the patient’s medical condition, the doctor may conduct further tests. For instance, patients with previous spinal fractures may require a CT scan. If the doctor detects osteoporosis or high bone loss, the patient may need to start taking medications or add weight bearing exercise to his or her daily routine.