Bone Up on DEXA!
In a previous post about prednisone, I mentioned that I have Bone Density Scans (commonly called DEXA) done every two years in order to monitor, you guessed it, my bone density. While there are drugs (like Actonel and Fosamax) that can actually help to rebuild your bones, a disease like Lupus, in combination with drugs like prednisone that literally eat away at the bones, requires that you not overlook the importance of monitoring your bone density. Here's a little bit more about DEXA, which is an x-ray usually performed at your doctor's office.
To start with, it is a non-invasive and painless procedure, and even better, it takes a mere minutes to perform. It is important that you wear loose fitting clothing, and you'll need to remove any garments that have notions made with metal (including an underwire), just as in any other x-ray. As I was gathering information for this post, it was also recommended that you not take calcium supplements for 24 hours prior to the scan, but be sure to check with your doctor on this before modifying any vitamin or medication regimen.
While there are two types of machines, my familiarity is with the Central DEXA device, which measures bone density in the hip and spine. These devices have a large, flat table and an "arm" suspended overhead. For my scans, I've always been asked to lie down on a padded table, where the x-ray generator is located below and an imaging device, or detector, is positioned above. The DEXA machine then sends a thin, invisible beam of low-dose x-rays with two distinct energy peaks through the bones being examined. One peak is absorbed mainly by soft tissue and the other by bone. The soft tissue amount can be subtracted from the total and what remains is my bone mineral density.
Throughout the procedure, my legs are supported on a padded box to flatten the pelvis and lower (lumbar) spine. To assess the hip, my foot is placed in a brace that rotates the hip inward slightly. In both cases, the detector is slowly passed over the area, generating images on a computer monitor.
Just as any other x-ray, you have to hold very still and may be asked to keep from breathing for a few seconds while the x-ray picture is taken to reduce the possibility of a blurred image. The overall procedure usually takes about 10-20 minutes, depending on the equipment used and the parts of the body being examined.
As far as procedures go, it's one of my favorites. It's quick, painless, and I don't need a prescription to go waste a few hours waiting in a x-ray facility. The results of the x-ray are generated immediately, and my doctor usually follows up with me within a few days on how my bone density is looking. If need be, we increase my calcium intake via supplements or food. As mentioned in my earlier post, for a few years, my bone density diminished drastically, due to the high doses of prednisone and disease activity, and even despite the fact that I was on the highest dose of Fosamax. But having stopped prednisone and increasing my calcium intake significantly, my bone density has actually improved. Score one for the patient!
DEXA bone densitometry is most often used to diagnose osteoporosis, a condition that often affects women after menopause but may also be found in men. Osteoporosis involves a gradual loss of calcium, causing the bones to become thinner, more fragile and more likely to break.
DEXA is also effective in tracking the effects of treatment for osteoporosis and other conditions that cause bone loss.The DEXA test can also assess an individual’s risk for developing fractures.
Bone density testing is strongly recommended if you:
- are a post-menopausal woman and not taking estrogen.
- have a personal or maternal history of hip fracture or smoking.
- are a post-menopausal woman who is tall (over 5 feet 7 inches) or thin (less than 125 pounds).
- are a man with clinical conditions associated with bone loss.
- use medications that are known to cause bone loss, including corticosteroids such as Prednisone, various anti-seizure medications such as Dilantin and certain barbiturates, or high-dose thyroid replacement drugs.
- have type 1 (formerly called juvenile or insulin-dependent) diabetes, liver disease, kidney disease or a family history of osteoporosis.
- have high bone turnover, which shows up in the form of excessive collagen in urine samples.
- have a thyroid condition, such as hyperthyroidism.
- have a parathyroid condition, such as hyperparathyroidism.
- have experienced a fracture after only mild trauma.
- have had x-ray evidence of vertebral fracture or other signs of osteoporosis.