In the beginning, that is from the 1960's, when a link between menopause and osteoporosis was first identified; estrogen treatment was the standard for preventing bone loss, however there was no fracture data, even though it was thought to be effective. This continued until the Women's Health Initiative (WHI) study in 2001 that published data on 6 years of treatment with hormone therapy that showed an increase in heart attacks and breast cancer. Even though the risks were small, 1 per 1500 users annually, patients were worried and there was a large drop off in estrogen use. In later analyses the WHI study showed that estrogen reduced fractures and actually prevented heart attacks in the 50-60 year age group. Estrogen alone appeared to be safer to use than estrogen + the progestin medroxyprogesterone acetate and actually reduced breast cancer.

Tumour-induced osteomalacia (TIO), also known as oncogenic osteomalacia, is a rare paraneoplastic disorder caused by tumours that secrete fibroblast growth factor 23 (FGF23). Owing to the role of FGF23 in renal phosphate handling and vitamin D synthesis, TIO is characterized by decreased renal tubular reabsorption of phosphate, by hypophosphataemia and by low levels of active vitamin D. Chronic hypophosphataemia ultimately results in osteomalacia (that is, inadequate bone mineralization). The diagnosis of TIO is usually suspected when serum phosphate levels are chronically low in the setting of bone pain, fragility fractures and muscle weakness. Locating the offending tumour can be very difficult, as the tumour is often very small and can be anywhere in the body. Surgical removal of the tumour is the only definitive treatment. When the tumour cannot be located or when complete resection is not possible, medical treatment with phosphate salts or active vitamin D is necessary. One of the most promising emerging treatments for unresectable tumours that cause TIO is the anti-FGF23 monoclonal antibody KRN23. The recent identification of a fusion of fibronectin and fibroblast growth factor receptor 1 (FGFR1) as a molecular driver in some tumours not only sheds light on the pathophysiology of TIO but also opens the door to a better understanding of the transcription, translocation, post-translational modification and secretion of FGF23, as well as suggesting approaches to targeted therapy. Further study will reveal if the FGFR1 pathway is also involved in tumours that do not harbour the translocation.

Background Regulatory agencies have concluded that sodiumglucose cotransporter 2 (SGLT2) inhibitors lead to ketoacidosis, but published literature on this point remains controversial. Methods We searched the FDA Adverse Event Reporting System (FAERS) for reports of acidosis in patients treated with canagliflozin, dapagliflozin, or empagliflozin (from the date of each drug’s FDA approval until May 15, 2015). We compared the number of SGLT2 inhibitor-related reports to reports of acidosis in patients treated with the 2 most commonly used DPP4 inhibitors: sitagliptin and saxagliptin. We estimated relative risks of acidosis by relating the number of reports to cumulative drug sales (a surrogate for patient exposure). Results FAERS contained 259 reports of acidosis (including 192 reports of ketoacidosis) for SGLT2 inhibitors compared with 477 reports of acidosis for DPP4 inhibitors (including 71 reports of ketoacidosis). Based on estimated patient exposure, the overall risk of developing acidosis was ~14-fold higher for SGLT2 inhibitors. Among 51 SGLT2 inhibitor-related reports with quantifiable metabolic information, 20 cases occurred in patients with type 1 diabetes (T1D), 25 in type 2 diabetes (T2D), and 6 in patients with unspecified type of diabetes. After excluding patients withT1D and focusing on patients identified as having T2D, we estimate that SGLT2 inhibitors were associated with ~7-fold increase in developing acidosis. Seventy-one percent had euglycemic ketoacidosis. Conclusions Our results support the FDA’s warning that SGLT2 inhibitors lead to ketoacidosis, as evidenced by an increased reporting rate for acidosis above that in a comparator population treated with DPP4 inhibitors.