The role of heparin in alleviating complement-mediated acute intravascular haemolysis

Heparin is commonly used as an anticoagulant but its many other pharmacologic properties are less well known. It has an important effect on complement regulation and has been shown in vitro to inhibit complement-mediated lysis of red cells. Although the beneficial effects of heparin for treatment of haemolytic anaemia were described many decades ago, its use in this scenario is not standard practice. Here we report a case where the use of heparin had a beneficial effect on a life-threatening episode of intravascular haemolysis. We also show unfractionated heparin to be more beneficial than low molecular weight heparin. We suggest that heparin has an important role to play in the management of complement-mediated haemolytic episodes.