Amiodarone-induced hyponatremia in an elderly patient

Amiodarone-Induced Hyponatremia in An Elderly Patient: A Rare Case Report

Amiodarone is an antiarrhythmic drug belonging to Vaughan-Williams Class III with additional Class IV effects, which is known to cause many adverse drug reactions (ADRs) necessitating close monitoring. In about 20% of patients, their therapy is discontinued due to adverse effects such as hepatic impairment, thyroid dysfunction, and several pulmonary complications. Although dyselectrolytemia is a common adverse reaction reported with many cardiac medications, the incidence of hyponatremia associated with amiodarone intake is not reported widely in the literature.We are reporting a case of a 73-year-old female patient, with hypertension and ischemic heart disease (IHD) receiving oral amiodarone, presenting with severe hyponatremia, requiring recurrent hospitalization. Amiodarone was found to be responsible after evaluating for the possible causes of hyponatremia.As the incidence of amiodarone-associated hyponatremia is unknown, and not many cases are reported, this case report serves to sensitize the clinician to consider amiodarone-induced hyponatremia as one of the differential diagnoses in cases of unexplained hyponatremia.

Amiodarone-Induced Syndrome of Inappropriate Antidiuretic Hormone: A Case Report and Review of the Literature

Amiodarone (Cordarone^®, Pfizer Inc) is an antiarrhythmic medication with a well-known toxicity profile, including rare cases of hyponatremia as a result of syndrome of inappropriate antidiuretic hormone (SIADH). We report on such a case in which a patient was found to be hyponatremic after evaluation. An 88-year-old male who presented to the emergency department was found to be hyponatremic secondary to amiodarone-induced SIADH following a fall, with possible seizure and traumatic brain injury. He had a history of hypertension, paroxysmal atrial fibrillation, emphysema, myocardial infarction, benign prostatic hyperplasia, chronic kidney disease, Meniere's disease, anemia, and gastroesophageal reflux. Upon admission, his urine sodium level was elevated, and his serum sodium, urine osmolality, and anion gap were below normal. In the setting of hyponatremia, the patient's amiodarone was held: he had been taking amiodarone 200 mg once daily for nine months prior to admission. He was treated with intravenous (IV) normal saline over four days. He was fluid-restricted and his sodium levels were closely monitored every two hours. Within 19 hours, his serum sodium levels had improved. Amiodarone was restarted approximately three days later. Upon follow-up after discharge, the patient remained on amiodarone for the next two months. His serum sodium level ranged from 126 mEq/L to 131 mEq/L over a two-week period. He was supplemented with sodium chloride tablets and has been otherwise stable. Amiodarone may cause acute or chronic SIADH, with a wide range of symptoms. Seizures have not been reported in the literature but our patient had a witnessed seizure, although his electroencephalogram (EEG) was negative. Syndrome of inappropriate antidiuretic hormone can occur with any formulation of amiodarone in a dose-dependent fashion. Our patient's sodium levels stabilized within two weeks after amiodarone was resumed. The mechanism of amiodarone-induced SIADH remains unclear.

Amiodarone-Induced Hyponatremia Masked by Tolvaptan in a Patient with an Implantable Left Ventricular Assist Device

A 43-year-old man was referred to our hospital in June 2014 because of severe heart failure. He was diagnosed with familial dilated cardiomyopathy and was administered oral tolvaptan and amiodarone for atrial and ventricular tachycardia. Since up-titration of carvedilol had failed and he was dependent on dobutamine, a left ventricular assist device (LVAD) was implanted. Tolvaptan and furosemide were both discontinued after LVAD implantation and he was discharged from the hospital. Thirteen months later, he was hospitalized for lethargy and hyponatremia of 108 mEq/L, with an antidiuretic hormone level of 2.5 pg/mL, which suggested syndrome of inappropriate antidiuretic hormone secretion (SIADH). We discontinued amiodarone and administered fludrocortisones. However, hyponatremia persisted for a few more days, eventually resulting in delirium and damage to the LVAD driveline. He received an urgent pump exchange and hyponatremia was gradually improved. We considered the possibility that amiodarone-induced SIADH was masked by tolvaptan therapy before LVAD implantation.