[A patient with inflammatory arthralgia, paraesthesia and atrial fibrillation].

A 61-year-old male patient had suffered from inflammatory arthralgia since 2014 and had been taking a proton pump inhibitor (PPI) for many years. Additionally, the patient was prescribed apixaban for atrial fibrillation. The blood tests on admission showed a marked hypomagnesemia with secondary hypocalcemia and hypokalemia. After discontinuation of the PPI and through substitution of magnesium, the blood results normalized completely and the patient was finally symptom-free. This case report underlines the important role of magnesium in rheumatology and presents the various mechanisms of action of magnesium.