The safety of using strontium for treating osteoporosis is a hotly debated topic. In my October 20, 2012 blog post, I voiced my concerns. In this post I would like to briefly add to this discussion.
The body absorbs and uses strontium as if it were calcium. With 99% of the body's calcium stores located in the skeleton, it's no wonder that high-dose strontium readily finds its way into bone. With it's high atomic number, strontium readily increases bone density as demonstrated on bone mineral density (DXA) exams. But calcium is important for more than just making our skeleton harder. Calcium is also necessary for nerve contractions, colon health, maintaining normal blood pressure, hormone production and enzymatic reactions. Because of this, there are concerns that replacing calcium with atoms of strontium in these key areas could have the potential to create adverse effects. For example, strontium can replace calcium at nerve synapses and retard the flow of nerve impulses. In fact, neurological disorders have been reported with strontium ranelate (Reginster et al., 2012) including memory loss (annual incidence 1.1%). Increased cancer risk is also a concern. A recent study out of China (Chen et al., 2012) found high strontium levels in premenopausal women to have a 124% increased risk of breast cancer.
Safety studies of strontium ranelate show increased risk for serious skin reactions (DRESS) and a 50% increased risk in venous thromboembolisms (VTE), including pulmonary embolisms. A new study published in France linked 199 severe adverse reactions to strontium ranelate (52% were cardiovascular related). These reports prompted safety concerns and a review by the European Medicines Agency (EMA/CHMP). Their official assessment report was issued on May 25, 2012 and concluded that "new contraindications and revised warnings should be included in the product information. Strontium ranelate should not be used in patients with VTE or those temporarily or permanently immobilized."
Reginster et al., 2012. Maintenance of antifracture efficacy over 10 years with strontium ranelate n postmenopausal osteoporosis. Osteoporosis International 23:1115-1122.
Chen et al., 2012. Urinary strontium and the risk of breast cancer: a case-control study in Guangzhou, China. Environmental Research Jan;112:212-7.
Jonville-Bera AP and Autret-Leca E. 2011. Adverse drug reactions of strontium ranelate (Protelos) in France. Presse Med Oct;40(10):e453-62.
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