Endocrine Abstracts

Introduction and Objectives: Proton-pump inhibitors (PPI) are some of the most commonly prescribed drugs, and they are generally well tolerated. However, their long-term use has been associated with adverse effects such as acute interstitial nephritis, Clostridium difficile infection. pneumonia, and (controversially) bone fractures, cardiovascular disease and dementia. The acidification of the intestinal milieu may interfere with TRMP6-mediated active absorption of magnesium in the intestinal mucosa. There have been several reports of symptomatic, even life-threatening (because of severe arrhythmia) hypomagnesemia associated with chronic use of PPIs. We hereby report a case of symptomatic hypocalcemia and hypomagnesemia in a patient which was resolved after switching pantoprazole to famotidine, in order to raise awareness about this uncommon adverse effect.

Methods: Review of the patient’s clinical records and of the relevant literature

Results: A 72 year old woman with history of obesity, hiatal hernia and gastroesophageal reflux, chronically treated with pantoprazole (>3 years) was admitted in the hospital emergency room with tingling and paresthesia in both arms and hands after an episode of acute gastroenteritis with vomiting and diarrhoea; Mild hypocalcemia (7.9 mg/dl) and severe hypomagnesemia (0.6 mg/dl) were detected, but her EKG showed no significant anomalies. Intravenous magnesium sulphate was administered and the patient’s symptoms were alleviated. She was discharged with calcium, magnesium and cholecalciferol supplements and referred to our Endocrinology clinic, after one month with new lab tests. The patient reported fatigue and occasional cramps and numbness in both hands but the Trousseau and Chvostek tests were negative. Plasma calcium, phosphate, PTH and calcifediol were normal but magnesium remained low (0.9 mg/dl) in spite of reported good compliance with the supplements and no new episodes of vomiting and diarrhoea. In a 24-h urine collection, calciuria was normal but magnesiuria was low. PPI-related hypomagnesemia with secondary hypocalcemia was suspected; the patient was switched from pantoprazole 40 mg to famotidine 20 mg daily. In the follow up visit after 3 months there were no symptoms and lab tests were normal; calcium, vitamin D and magnesium supplements were withdrawn.

Conclusions: Severe symptomatic hypomagnesemia is an uncommon adverse effect associated with the chronic use of PPIs, and it is resistant to the use of oral magnesium supplements. PPIs are probably overused, and deprescription should be considered in chronic users unless there is a clear justification. H2 blockers can be used as an alternative to PPIs if needed.