title: An approach to the diagnosis and management of a case presenting with recurrent hypomagnesemia secondary to the chronic use of a proton pump inhibitor.
abstract: OBJECTIVE
  Magnesium is an important electrolyte for very many cell functions and its deficiency may lead to a wide spectrum of diseases. We report a clinical case of hypomagnesemia resulting from the chronic use of a proton pump inhibitor (PPI). PPIs are drugs widely used in medical practice, and a growing number of cases of PPIs causing hypomagnesemia have been described. Our aim was to monitor the clinical and electrolyte findings during recovery from hypomagnesemia caused by long-term PPI use.
  
  
  RESULTS
  A 65-year old female who had been using omeprazole for 10 years, presented with arrhythmia and paresthesia of the lower and upper limbs that had been attributed to severe hypomagnesemia, hypocalcemia, and hypoparathyroidism. Her laboratory tests revealed the following results: magnesium 0.6 mg/dL (NR: 1.5 to 2.5 mg/dL), calcium 7.3 mg/dL (NR: 8.5 to 10.2 mg/dL), parathyroid hormone (PTH) 13.3 pg/mL (NR: 15 to 65 pg/mL), and low urinary calcium and magnesium excretion. Her electrocardiogram disclosed typical, prolonged QT interval, ST depression, and U waves. We discuss the differential diagnoses, pathophysiology, and reversibility of symptoms after effective treatment of the hypomagnesemia.
  
  
  CONCLUSIONS
  this report emphasizes that even if long-term PPI users appear largely asymptomatic, life-threatening arrhythmias can present very suddenly. Long-term PPI users should be monitored for otherwise unexplained hypomagnesemia, hypocalcemia, functional hypoparathyroidism and associated symptoms.
authors.affiliation: Laboratory of Molecular and Translational Endocrinology, Department of Medicine, Escola Paulista de Medicina, Universidade Federal de São Paulo, Brazil, Bone Metabolism Unit, Endocrinology Division, Department of Medicine, Escola Paulista de Medicina, Universidade Federal de São Paulo, Brazil.
authors.forename: Lívia Marcela
authors.initials: LM
authors.lastname: dos Santos
authors.affiliation: Endocrinology Unit, Hospital do Servidor Público do Estado de São Paulo (HSPE-IAMSPE), São Paulo, Brazil.
authors.forename: Ricardo Ayello
authors.initials: RA
authors.lastname: Guerra
authors.affiliation: Bone Metabolism Unit, Endocrinology Division, Department of Medicine, Escola Paulista de Medicina, Universidade Federal de São Paulo, Brazil.
authors.forename: Marise
authors.initials: M
authors.lastname: Lazaretti-Castro
authors.affiliation: Laboratory of Molecular and Translational Endocrinology, Department of Medicine, Escola Paulista de Medicina, Universidade Federal de São Paulo, Brazil, Bone Metabolism Unit, Endocrinology Division, Department of Medicine, Escola Paulista de Medicina, Universidade Federal de São Paulo, Brazil.
authors.forename: José Gilberto H
authors.initials: JG
authors.lastname: Vieira
authors.affiliation: Endocrinology Unit, Hospital do Servidor Público do Estado de São Paulo (HSPE-IAMSPE), São Paulo, Brazil.
authors.forename: Evandro de Souza
authors.initials: Ede S
authors.lastname: Portes
authors.affiliation: Laboratory of Molecular and Translational Endocrinology, Department of Medicine, Escola Paulista de Medicina, Universidade Federal de São Paulo, Brazil.
authors.forename: Magnus R
authors.initials: MR
authors.lastname: Dias-da-Silva
mesh_terms: D000368:Aged; D001145:Arrhythmias, Cardiac / Q000097:blood / Q000139:chemically induced; D015415:Biomarkers / Q000097:blood; D003937:Diagnosis, Differential; D015536:Down-Regulation; D004562:Electrocardiography; D005260:Female; D006801:Humans; D006996:Hypocalcemia / Q000097:blood / Q000139:chemically induced; D007011:Hypoparathyroidism / Q000097:blood / Q000139:chemically induced; D008274:Magnesium / Q000097:blood*; D008659:Metabolic Diseases / Q000097:blood / Q000139:chemically induced* / Q000175:diagnosis / Q000628:therapy; D009853:Omeprazole / Q000009:adverse effects*; D010292:Paresthesia / Q000097:blood / Q000139:chemically induced; D011237:Predictive Value of Tests; D054328:Proton Pump Inhibitors / Q000009:adverse effects*; D012307:Risk Factors; D016896:Treatment Outcome
chemical_list: D015415:Biomarkers; D054328:Proton Pump Inhibitors; D008274:Magnesium; D009853:Omeprazole
keywords: hypocalcemia; hypokalemia; hypomagnesemia; omeprazole