Table 4 Summary of the causes of MAHA

Features common to all causes of MAHA

Anaemia (Hb < 8 g/dL)

Thrombocytopoenia (platelets < 140 × 10(9)/L)

Red Blood Cell fragments, Schistocytes and helmet cells on blood film

Negative Coombs test (IgG autoantibodies to individual's red blood cells)

Possible multi-system involvement

HUS type I (Shiga-like / Verotoxin associated)

Associated with Verotoxin (Shiga-like) E. coli

O157 infection

Prodrome of diarrhoea, often bloody, 3-5 days before onset

Typically affects children < 5 yrs

Commonly acute renal failure

HUS type II (Non Shiga-like)

Not thought to be associated with diarrhoea

TTP

Neurological symptoms predominant

Acute kidney injury

Pyrexia

Disseminated Intravas-cular Coagulation

Activation of the intravascular clotting cascade

Consumption of clotting factors and fibrinogen

Consumption of platelets

Raised INR, PT, APTTR

Other causes

Aortic Stenosis / replacement valve

Scleroderma renal crisis

Severe glomerulonephritis malignant hypertension, pregnancy associated microangiopathy (incl. pre-eclampsia, HELLP syndrome) infective (shigella, TB, E. Coli)

Drug related (e.g. Heparin - Heparin Induced Thrombocytopoenia (HIT))