Better measurements for better predictions

The genetic disorder Duchenne muscular dystrophy (DMD) occurs when there is a lack of the protein dystrophin, causing progressively weak muscle development in children and a shorter life span. Once children begin steroid treatment, their bones become very fragile and experience delays in growth. Dual X-ray absorptiometry, or DXA scans, which are used to monitor the condition of the bones, compare the bones of a healthy volunteer to the bones of a person with DMD. However, people with DMD usually have bones that are far younger in development than their actual age, so these scans are usually inaccurate.

Researchers at the University of Iowa have found a more reliable way. Asma Al Zougbi, MD, associate of Endocrinology and Metabolism, Amal Shibli-Rahhal, MD, MS, clinical professor of Endocrinology and Metabolism and Katherine Mathews, MD, professor of Neurology published their new approach for analyzing bone density in people with DMD in the journal Muscle & Nerve.

“We decided to compare the bone density of these patients with that of people whose age matches their bone age, rather than their actual chronological age,” Al Zougbi said. “Our study results raise the question of whether using bone-age rather than chronological-age might give a better estimate of risk of fractures. This would require a longer term and larger study, but would be very clinically meaningful.”

The idea to compare bone age rather than physical age came to Shibli-Rahhal after she struggled with how to interpret the DXA scans of her pediatric patients with DMD. Since she could not determine the condition of her patient’s bones correctly, there was need for a solution that could guide treatment.

“Since our ultimate goal is to prevent fractures, it is important to have an accurate estimate of the patient’s risk of fracture in order to determine the best therapy,” Shibli-Rahhal said.

As a research fellow who studies muscle development and steroids at the Abboud Cardiovascular Research Center, Al Zougbi is thankful for her first publication. “I hope to be able apply for a career development award later this year so I can continue my work, with the ultimate goal of finding mechanisms to prevent or treat muscle atrophy and thus preserve human health,” Al Zougbi said.