Iranian Heart Association Iranian Heart Journal 24 2 2023 04 01 Heparin-Induced Hyperkalemia Following Heart Surgery: A Case Report 104 107 169030 EN Franak Kargar Rajaie Cardiovascular, Medical and Research Center, Iran University of Medical Sciences, Tehran, IR Iran. Ali Zahedmehr Cardiovascular Intervention Research Center, Rajaie Cardiovascular, Medical and Research Center, Iran University of Medical Sciences, Tehran, IR Iran. Zahra Shafii Rajaie Cardiovascular, Medical and Research Center, Iran University of Medical Sciences, Tehran, IR Iran. 0000-0002-6906-0437 Touraj Babaee Rajaie Cardiovascular, Medical and Research Center, Iran University of Medical Sciences, Tehran, IR Iran. Sepideh Banar Heart Valve Disease Research Center, Rajaie Cardiovascular Medical and Research Center, Iran University of Medical Sciences, Tehran, IR Iran. Yousef Rezaei Heart Valve Disease Research Center, Rajaie Cardiovascular Medical and Research Center, Iran University of Medical Sciences, Tehran, IR Iran. 0000-0002-6804-4232 Saeid Hosseini Heart Valve Disease Research Center, Rajaie Cardiovascular Medical and Research Center, Iran University of Medical Sciences, Tehran, IR Iran. Journal Article 2022 04 24 Heparin is widely used in patients undergoing cardiac surgeries on cardiopulmonary bypass; however, it can cause some complications, mainly including bleeding and thrombocytopenia. Heparin-induced hyperkalemia is a rare and less recognized adverse effect of heparin therapy that can lead to serious morbidities. Herein, we describe a 69-year-old Caucasian woman with coronary artery disease who underwent coronary artery bypass graft surgery. The postoperative electrocardiogram was normal without any signs of ischemia or arrhythmia. After the patient was transferred to the intensive care unit, her potassium level was 5.8 mEq/L, which remained high. She had not perioperatively received any causative agent of hyperkalemia. All laboratory tests were within normal ranges. Despite adequate diuresis, a relatively steady state of renal function, and hyperkalemia treatment, including intravenous glucose and furosemide and insulin infusion, the patient’s potassium level increased progressively. All etiologies of hyperkalemia were ruled out, and consequently heparin-induced hyperkalemia was suspected.<strong><em> (Iranian Heart Journal 2023; 24(2): 104-107)</em></strong> https://journal.iha.org.ir/article_169030_95e800f3eac69dc5402c51559e83da31.pdf