In-vivo measurement of strontium incorporation and retention in human bone using an x-ray fluorescence system

Stronthium (Sr), found in nature and human skeleton [sic], exerts beneficial or detrimental effects, depending on levels. Previous strontium studies in humans and animals showed bone mineral density and bone strength increases. However, its exact mechanism of therapeutic action is not fully understood. The purpose of this study was to investigate strontium incorporation and retention over time, in healthy and osteoporotic/osteopenic individuals, using the non-invasive, in-vivo X-Ray Fluorescence (IVXRF) system developed and optimized by Pejovic-Milic 2004 and Zamburlini 2008. Nine individuals, self-supplementing with strontium, were recruited and measured at their finger and ankle, representing cortical and trabecular bone. Using ¹²⁵I brachytherapy seeds as the radiation photon source, each measurement lasted thirty minutes. All individuals showed an initial rapid uptake of strontium within 2-5 months followed by slower increases, suggesting that strontium incorporation and retention is a result of two different mechanisms and is dependent on the bone remodeling cycle.