October - December 2015, Volume 11, Issue 4

Serban RC, Scridon A, Petri R, Pascanu I, Dobreanu D

Atrial Electric Instability and Conduction Disorders in the Setting of Hyponatremia Induced by Combined Non-Psychogenic Polydipsia and Diuretic Therapy

Acta Endo (Buc) 2015, 11 (4): 501-506
doi: 10.4183/aeb.2015.501

Context. Non-psychogenic polydipsia-induced hyponatremia is a rare clinical finding. The effects of severe hyponatremia on the electrical activity of the heart in this setting are far from clear. Case report. Resting ECG and 24-h ambulatory ECG monitoring performed in an 80-year-old hypertensive female accusing nonspecific symptoms of confusion, lethargy, disorientation, nausea, and palpitations, demonstrated significant intraatrial and atrioventricular conduction disorders and numerous atrial tachyarrhythmia episodes. Laboratory analysis revealed severe hyponatremia (108 mEq/L) as only significant disorder. Extensive endocrine, neurological, cardiology, and pulmonary examinations excluded the most common causes of hyponatremia, including the inappropriate antidiuretic hormone secretion syndrome. Careful history revealed excessive voluntary water intake of up to 6 L/day and low sodium intake, associated with long-term thiazidelike diuretic treatment. Correction of sodium levels was associated with complete resolution of both atrial arrhythmias and conduction disorders. Conclusions. This report presents the first case of severe hyponatremia caused by combined non-psychogenic polydipsia and thiazide-like diuretic use complicated with reversible cardiac conduction disorders and atrial arrhythmias. The close temporal relationship between the fully reversible cardiac electric abnormalities and severe hyponatremia strongly indicates hyponatremia as key feature in the pathogenesis of these electric abnormalities.

Keywords: hyponatremia, non-psychogenic polydipsia, atrial arrhythmias, conduction disorders

Correspondence: Alina Scridon MD, University of Medicine and Pharmacy of Tîrgu Mures, Dept. of Physiology, 38 Gheorghe Marinescu Street, Tîrgu Mures, 540139, Romania, E-mail: alinascridon@gmail.com