Thrombotic microangiopathy

Thrombotic microangiopathies (TMA) are characterised by the presence of thrombocytopaenia, microangiopathic haemolysis (haemolysis in the small vessels), and microvascular thrombi. The main TMAs are haemolytic uremic syndrome (HUS) and thrombotic thrombocytopenic purpura (TTP).

Microthrombi cause ischaemic organ dysfunction. In HUS this is mostly seen in the glomeruli and may lead to acute kidney injury, while TTP involves the neurological endothelial cells and cause neurological symptoms. However, TTP and HUS are often considered together as they have similar aetiology and have overlaps in symptoms. Many patients are best fit for the diagnosis TTP-HUS as they can suffer from seizures or coma and AKI.