Hypomagnesemia and Teriparatide in Osteoporosis: Incidence and Predictive Factors

Presentation Number: SUN 320
Date of Presentation: April 2nd, 2017

Marie-Josée Bégin*1, Louis-Georges Ste-Marie2, Jean-Hugues Brossard2, Jean Ethier3 and Agnes Rakel4
1Centre hospitalier de l'Université de Montreal, Montréal, QC, Canada, 2Centre hospitalier de l'Université de Montréal, Montreal, QC, Canada, 3Centre hospitalier de l' Université de Montreal, Montreal, QC, Canada, 4Centre hospitalier de l'Université de Montréal, Montréal, QC, Canada

Abstract

Background

In our clinical experience, we have encountered a patient with severe hypomagnesemia associated with muscular cramps refractory to magnesium supplements. Some trials have reported hypomagnesemia as an adverse effect, but this issue had never been studied specifically.

Methods

Our objective was twofold: 1-) determine the incidence of hypomagnesemia (serum magnesium ˂ 0.7 mmol/L) associated to teriparatide in a retrospective cohort and 2-) identify the predisposing factors to hypomagnesemia in this cohort. We reviewed the files of 53 patients treated for severe osteoporosis with teriparatide for 6 to 24 months between 2008 and 2016. Serum magnesium level was measured at 0, 3, 6, 18 and 24 months.

Results

In the full cohort, we observed an average decrease of serum magnesium of 0.075 mmol/L, 0.069 mmol/L, 0.085 mmol/L, 0.086 mmol/L (p ˂ 0.001) at 3, 6, 12 months and at the end of the treatment, respectively. The cumulative incidence of hypomagnesemia during the course of treatment with teriparatide was 35.9 % (19 patients). Patient’s age (65.1 vs. 71.1 years-old; p = 0.05) and lower baseline level of magnesium before teriparatide treatment (0.81 mmol/L vs. 0.85 mmol/L; p = 0.03) were risk factors of teriparatide induced hypomagnesemia. The average decrease of serum magnesium was greater in the patients who developed hypomagnesemia compared to normomagnesemic patients at 3 months (0.110 mmol/L vs 0.054 mmol/L; p=0.02), 6 months (0.139 mmol/L vs 0.036 mmol/L; p˂0.001) and 12 months (0.156 mmol/L vs 0.048 mmol/L; p˂0.001). Serum calcium, phosphorus, creatinine and PTH remained normal throughout the treatment period.

Conclusions

Following the use of teriparatide for severe osteoporosis, we observed a statistically significant decrease in the serum magnesium levels. Age and baseline magnesium were significant predictors of hypomagnesemia. We should consider closer monitoring of the serum magnesium level in patients with risk factors such as older age, low serum magnesium at baseline, as well as multiple medications and comorbidities influencing serum magnesium level.

 

Disclosure: LGS: Consultant, Amgen, Consultant, Eli Lilly & Company, Consultant, Merck & Co.. AR: , Astella, , Boehringer Ingelheim, , Astella, , Merck & Co., , Eli Lilly & Company, , Novo Nordisk, , Roche Pharmaceuticals, , Sanofi, , Sanofi, , Novartis Pharmaceuticals, , Novartis Pharmaceuticals, , Genzyme. Nothing to Disclose: MJB, JHB, JE