Shroff R, Fewtrell M, Heuser A, et al. - In the present study, the researchers sought to analyze naturally occurring stable (non‐radioactive) calcium (Ca) isotopes in different body pools as a potential biomarker of bone mineral balance (BMB). They measured Ca isotopes, biomarkers, and BMD by DXA and tibial peripheral quantitative CT in 117 healthy candidates. Using a compartment model, the link between bone Ca gain and loss was calculated. Findings suggested that naturally occurring Ca isotope ratios in different body compartments can provide a novel, non‐invasive method for evaluating bone mineralization. Defining an effective BMB biomarker may form the basis for future studies examining Ca dynamics in disease states and the effect of bone homeostasis-influencing treatments.