title: Cardiac work up in primary renal hypokalaemia-hypomagnesaemia (Gitelman syndrome).
abstract: BACKGROUND
  Potassium and magnesium depletion prolongs the duration of the action potential of the cardiomyocyte, which predisposes to ventricular arrhythmias. In addition, potassium or magnesium depletion might impair cardiac performance and facilitate coronary artery thrombosis.
  
  
  METHODS
  Continuous 24-h ambulatory electrocardiographic monitoring, treadmill exercise testing and echocardiography were assessed in 21 patients (11 female and 10 male subjects, aged 5.9-39, median 19 years) with primary renal hypokalaemia-hypomagnesaemia.
  
  
  RESULTS
  The QT interval corrected for heart rate was normal (between 379 and 430 ms) in 10 and slightly to moderately prolonged in the remaining 11 patients (between 446 and 509 ms). Plasma potassium, magnesium and bicarbonate were similar in patients with normal and in those with prolonged QT interval. Continuous ambulatory electrocardiography over 24 h and exercise testing did not detect significant abnormalities of cardiac rhythm or features suggestive of myocardial ischaemia. Finally, echocardiographic and Doppler assessment failed to reveal any abnormalities in myocardial morphology and function.
  
  
  CONCLUSIONS
  The QT interval is often prolonged in primary renal hypokalaemia-hypomagnesaemia, confirming that potassium and magnesium depletion tends to prolong the duration of the action potential of the cardiomyocyte. The results of continuous ambulatory electrocardiography, exercise testing and echocardiography are reassuring. Nonetheless, we assume that dangerous cardiac arrhythmias may occur in patients with very severe hypokalaemia, during medication with drugs that prolong the QT interval or in the context of short-term non-adherence to the recommended regimen of care.
authors.affiliation: Pediatric Renal Unit, University of Milan Medical School, Clinica De Marchi, Italy.
authors.forename: Pietro E G
authors.initials: PE
authors.lastname: Foglia
authors.forename: Alberto
authors.initials: A
authors.lastname: Bettinelli
authors.forename: Camillo
authors.initials: C
authors.lastname: Tosetto
authors.forename: Cinzia
authors.initials: C
authors.lastname: Cortesi
authors.forename: Laura
authors.initials: L
authors.lastname: Crosazzo
authors.forename: Alberto
authors.initials: A
authors.lastname: Edefonti
authors.forename: Mario G
authors.initials: MG
authors.lastname: Bianchetti
mesh_terms: D000293:Adolescent; D000328:Adult; D001145:Arrhythmias, Cardiac / Q000453:epidemiology / Q000503:physiopathology*; D002648:Child; D002675:Child, Preschool; D015897:Comorbidity; D015150:Echocardiography, Doppler; D015716:Electrocardiography, Ambulatory; D005080:Exercise Test; D005260:Female; D006329:Heart Conduction System / Q000000981:diagnostic imaging / Q000503:physiopathology*; D006801:Humans; D007008:Hypokalemia / Q000453:epidemiology / Q000503:physiopathology*; D007674:Kidney Diseases / Q000453:epidemiology / Q000503:physiopathology*; D008274:Magnesium / Q000097:blood*; D008297:Male; D013577:Syndrome
chemical_list: D008274:Magnesium