Strontium

Strontium is a naturally occurring alkaline earth metal that shares chemical properties with calcium and preferentially incorporates into bone mineral at sites of active remodeling. The pharmaceutical form, strontium ranelate (Protelos), was approved in Europe for osteoporosis treatment based on large randomized trials (SOTI and TROPOS) showing 37–41% reductions in vertebral fracture risk and 16% reductions in non-vertebral fractures. Its dual mechanism involves both stimulation of osteoblast-mediated bone formation and inhibition of osteoclast-mediated bone resorption. However, post-marketing surveillance revealed increased cardiovascular risks, including myocardial infarction and venous thromboembolism, leading the EMA to restrict its use to severe osteoporosis patients without cardiovascular disease. Over-the-counter strontium citrate supplements are marketed as a bone health alternative but lack the clinical trial evidence of the ranelate salt. Importantly, strontium artificially inflates DXA bone density measurements by approximately 10% due to its higher atomic number, which must be accounted for in clinical interpretation.