Anticoagulation and kidney injury: rare observation or common problem?

Vitamin K antagonists (VKAs), which inhibit the synthesis of the coagulation factors II, VII, IX and X, have been in clini- cal use since the 1950s to treat thrombotic disease. Re- cently, new indications for long-term anticoagulation have been recognised. Consequently the number of patients prescribed long-term anticoagulant therapy with VKAs is in- creasing. Warfarin is the most commonly prescribed VKA, but acenocoumarol and phenprocoumon are also widely used in Europe. Patients with chronic kidney disease (CKD) are at a relatively higher risk of thromboembolic disease. In addition, patients on long-term warfarin often have mul- tiple comorbidities placing them at risk of kidney disease. Therefore, warfarin is a commonly used drug in CKD patients. There are obvious dangers of overanticoagulation, most im- portantly the risk of haemorrhage, a complication which is twofold more common in patients with CKD (1). Maintaining warfarin within its narrow therapeutic range can be more dif- ficult in patients with CKD, and overt, hypovolaemic blood loss resulting from overanticoagulation can precipitate acute kidney injury (AKI). However, warfarin use alone was not tra- ditionally thought of as a cause of kidney injury.