Improvement in Serum Magnesium Levels With Sodium-Glucose Cotransporter 2 Inhibitors

Sodium-glucose cotransporter 2 inhibitors (SGLT2i) are associated with a modest but significant increase in serum magnesium levels. This report describes improvement in serum magnesium and associated symptoms after initiating SGLT2i therapy in a patient with refractory hypomagnesemia. A 58-year-old woman presented with persistent hypomagnesemia refractory to oral magnesium supplements. She had history of type 2 diabetes mellitus, hypothyroidism, fibromyalgia, and degenerative disk disease. The cause of hypomagnesemia was attributed to excessive renal losses. Laboratory investigations revealed serum magnesium of 1.2 mg/dL with fractional excretion of magnesium of 8.9%. She was started on empagliflozin 10 mg daily. Within 4 weeks of therapy, her serum magnesium level corrected with symptomatic improvement, which was sustained a few weeks later. Subsequently, her oral magnesium supplements dose was reduced. SGLT2i has been shown to improve magnesium levels in patients with urinary magnesium wasting. Several mechanisms have been postulated, but the exact physiology remains unknown. SGLT2i have been efficacious for glycemic control, renal protection, decreasing the risk of atherosclerotic cardiovascular disease events, and cardiac mortality in patients with diabetes. In addition, renal and cardiac benefits are also demonstrated in patients without diabetes. This observation demonstrates that SGLT2i can improve the management of patients with otherwise intractable hypomagnesemia.

TRPC3 mediates hyperexcitability and epileptiform activity in immature cortex and experimental cortical dysplasia

Neuronal hyperexcitability plays an important role in epileptogenesis. Conditions of low extracellular calcium (Ca) or magnesium (Mg) can induce hyperexcitability and epileptiform activity with unclear mechanisms. Transient receptor potential canonical type 3 (TRPC3) channels play a pivotal role in neuronal excitability and are activated in low-Ca and/or low-Mg conditions to depolarize neurons. TRPC3 staining was highly enriched in immature, but very weak in mature, control cortex, whereas it was strong in dysplastic cortex at all ages. Depolarization and susceptibility to epileptiform activity increased with decreasing Ca and Mg. Combinations of low Ca and low Mg induced larger depolarization in pyramidal neurons and greater susceptibility to epileptiform activity in immature and dysplastic cortex than in mature and control cortex, respectively. Intracellular application of anti-TRPC3 antibody to block TRPC3 channels and bath application of the selective TRPC3 inhibitor Pyr3 greatly diminished depolarization in immature control and both immature and mature dysplastic cortex with strong TRPC3 expression. Epileptiform activity was initiated in low Ca and low Mg when synaptic activity was blocked, and Pyr3 completely suppressed this activity. In conclusion, TRPC3 primarily mediates low Ca- and low Mg-induced depolarization and epileptiform activity, and the enhanced expression of TRPC3 could make dysplastic and immature cortex more hyperexcitable and more susceptible to epileptiform activity.