Natural stable calcium isotope ratios: a new gold standard for bone balance?

Bone calcium balance is the net gain, loss, or equilibrium of calcium moving to and from bone, which reflects bone balance. There are currently no clinically available tools for measuring real-time bone balance. In this issue, Shroff et al. demonstrate the use of natural stable calcium isotope ratios as a novel biomarker of bone balance in children with chronic kidney disease on dialysis that is highly repeatable and associated with radiological and biochemical markers of bone metabolism.