Endocrine Abstracts

Introduction: Heparin is extensively used amongst different medical and surgical specialities for prophylaxis and treatment of venous thromboembolism and suspected coronary syndromes. Hyperkalaemia is known to occur as an effect of heparin treatment through its action on the renin-angiotensin system, especially when used at treatment doses. Hyperkalaemia is a serious electrolyte disturbance, which may precipitate potentially fatal cardiac arrhythmias. We describe a case of a patient developing hyperkalaemia secondary to a prophylactic dose of low-molecular weight heparin.

Case report: A 65-year-old man with ischaemic heart disease, type 2 diabetes and peripheral vascular disease was admitted under the vascular surgical team with ischaemic right leg. He was commenced on prophylactic low-molecular weight heparin. Four days into his hospital stay he became hyperkalaemic with serum potassium of 6.1 mmol/l (normal 4.5–5.3 mmol/l). The potassium level remained persistently elevated in spite of stopping the ACE inhibitor and spironolactone, which he was on for several years. He responded only briefly to insulin–dextrose infusions. The hyperkalaemia resolved gradually on discontinuing the prophylactic heparin.

Discussion: Compared to normal population, hyperkalaemia is more prevalent among diabetics. Hyperglycaemia causes an increase in extracellular osmolality, which then leads to elevated potassium levels. Hyperkalaemia will be prolonged if duration of heparin therapy is prolonged before discontinuation.

Conclusion: This case illustrates the potentially harmful effect of low dose low-molecular weight heparin. Although there are warnings in the British National Formulary about the risks of hyperkalaemia with heparin use, awareness of this side effect amongst medical and surgical staff appears to be low. With increasing use of prophylactic heparin amongst medical patients, heparin-associated hyperkalaemia may well be seen more frequently.