The Osteoporosis Oracle

It is estimated that over 200 million people worldwide suffer from osteoporosis (1). The condition, which disproportionately affects adults over the age of 50, is also a concern for astronauts, who shed 1–2 percent of their bone density per month (2). Now, a new test developed by scientists at Arizona State University and The Mayo Clinic, in association with NASA, could monitor the development of asymptomatic bone disease in real-time, earlier than current tests, after being verified by astronauts posted on the international space station (3).

The method, unveiled at the Goldschmidt conference, uses the calcium isotopes, 42Ca and 44Ca, as biomarkers for bone diseases such as osteoporosis and multiple myeloma. The team discovered that these isotopes, which are absorbed from the blood during bone growth and development, are also released back into the blood stream once bones begin to break down. Using mass spectrometry, the researchers measured relative ratios of the isotopes from serum and urine samples to calculate whether bone is being resorbed or formed.

Though the initial study assessed bed-bound patients who are known to experience bone mass loss, the focus moved to the skies for a less controlled population. In collaboration with NASA, the team measured calcium isotope ratios from 30 astronauts before, during and after their missions to the international space station. The results were consistent with those of bed-bound patients, finding an increase in calcium excretion. The study was expanded to 71 patients with multiple myeloma; those who tended to lose the lighter 42Ca isotope, also seemed to be the patients with a more active form of the disease.

“The big advantage of these measurements is that they show what is happening in the bone in real-time, whereas traditional bone health measurements, such as dual-energy x-ray absorptiometry (DXA) scans, show what has happened, when damage may have already been done,” claims Ariel Anbar, President’s Professor at Arizona State University. The advantage of performing a simple urine or blood test, rather than undergoing x-ray testing, is obvious too.

It’s hoped that this new method may also evaluate and optimize the efficiency of bone-specific therapies in the future. Anbar, a geochemist, now wants to bridge the understanding gap between geochemists, and biomedical researchers, who may struggle to understand the test or inaccurately believe it to involve radioactive isotopes. “Closing this gap is vital for developing the technique,” says Anbar.