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Building Bones in Thalassemia Patients
New Bone Density Study in Patients with Thalassemia Shows Need for Intervention at Younger Ages

A new study by CHORI scientists Ellen Fung, PhD, Elliott Vichinsky, MD, and their colleagues published in the April issue of Bone, underscores the need for improved intervention in thalassemia patients when they are young to help prevent osteoporosis, or low bone mass, in adulthood.

"What we've shown in this study is that we are still seeing dramatic differences in the bone mass of patients with thalassemia compared to healthy controls, even when we are able to use statistical techniques to control for bone scanning artifacts that could make bone mass look low even when it isn't," says Dr. Fung.

"In addition, we've used bone markers to determine that in thalassemia patients, bone formation itself is reduced, indicating that we need to focus on bone health interventions before a patient reaches adulthood."

“We are still seeing dramatic differences in the bone mass of patients with thalassemia compared to healthy controls.”

Low bone mass is a significant problem in the thalassemia population, with approximately 50 to 90 percent of adults with thalassemia presenting with low bone mass. While in previous decades thalassemia treatment was more focused on immediate concerns over managing iron overload and its associated problems, such as heart disease and cardiac events, improvements in iron overload treatment has improved patients' long-term outlook.

"What this means for patients is that now that they are living longer with less immediate threats, they are at increased risk for bone pain and fracture at a young age," says Dr. Fung.
“Most of us think of osteoporosis as an old lady's disease, something that happens to grandmothers who fall and break their hips. With thalassemia patients, however, fragility fractures can happen much earlier in life.”
As Dr. Fung explains, "Patients may come in because of some kind of back pain and discover a fracture in their spine. These kinds of fractures are common, and happen not because of vigorous physical activity, but because the bone mass is simply that low."

Researchers have been looking at bone health in thalassemia patients for decades but typically have used only a two-dimensional bone-scanning tool, called dual energy x-ray absorptiometry (DXA). DXA can over-estimate low bone mass, however, simply because its two-dimensional imagery cannot account for potential artifacts, such as bone size, muscle mass or height.

"All of these elements that are paritcular to thalassemia patients lower than average height, body size and muscle mass, could be creating potential artifacts that prevent us from accurately assessing patients' bone density," says Dr. Fung.
With the new Bone study, however, Dr. Fung and her colleagues have for the first time utilized two different types of scanning, the DXA and a three-dimensional scanning tool called quantitative computed tomography (pQCT), in order to control for these potential artifacts.

"What our results show is that even after controlling for potential artifacts, thalassemia patients still have extremely low bone mass when compared with healthy counterparts," Dr. Fung says. "Not only that, but we were able to use the pQCT to assess different types of bone and overall bone strength in thalassemia patients as well."

Dr. Fung discovered that the size of the bones themselves were much smaller in thalassemia patients than in healthy controls, and had a significantly smaller outside circumference.

"In addition, the cortical shell, which is the part of the bone which makes it strong both in terms of compression and lateral movement, was also significantly thinner in thalassemia patients than healthy controls," says Dr. Fung.

The general approach to treating low bone mass in thalassemia patients has been to prescribe osteoporosis drugs once these patients reach adulthood. Osteoporosis medications generally are used to decrease bone breakdown, which is elevated in thalassemia. The results of Dr. Fung's study, however, indicate that this is potentially too little, too late. Not only is bone breakdown elevated in thalassemia, but bone formation is significantly reduced.

“What these results really tell us is that we need to focus on the problem much earlier, when bone formation is at its peak. This means looking at younger patients, and focusing on ways to increase bone formation through exercise and diet.”

Currently Dr. Fung is undertaking studies to asses different approaches to enhancing bone formation, including using vibration platforms, vitamin D and zinc supplementation, as well as looking at increasing physical activity in patients by fully characterizing patients' current activity to see how best to improve it.

"Even with all the other significant issues in thalassemia that deserve attention, if we want to have any affect on bone mass in thalassemia patients we absolutely must start looking at ways of building patients' bones when they are younger."


Friday, June 10, 2011 9:56 AM

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