Microangiopathic hemolytic anemia

Introduction

Microangiopathic hemolytic anemia (MAHA) = variety of conditions that result in damaged endothelium of small vessels causing platelet aggregation and fibrin deposition which leads to shearing forces within these small vessels causing an intravascular fragmentation hemolysis

Diagnosis

Clinical features + heme labs with red blood cell fragments or schistocytes.^[1]
May have bleeding and thrombosis

Differential Diagnosis

Most common causes: DIC, TTP, HUS
Other medical causes: malignant hypertension, HELLP, Antiphospholipid Syndrome (APS), scleroderma, Paroxysmal Nocturnal Hemoglobinuria (PNH), malignancy, renal allograft rejection, vasculitides like polyarteritis nodosa and Wegener's granulomatosis
Drugs: chemotherapy; Clopidogrel (Plavix) associated with TTP
Nonvascular causes: prosthetic valve (more common w/ mechanical, more common at aortic valve), LVAD, TIPS, coil embolization, patched AV shunt, AVM

Work-Up

Peripheral smear, hemoglobin, platelets, PT/INR, PTT, fibrinogen, FDPs, D-dimer, haptoglobin, LDH, bilirubin
- Schistocytes (aka Helmet cells) secondary to fragmentation hemolysis classic finding on peripheral smear

Lab Findings

Schistocytes
High: +/- LDH and unconjugated bilirubin
Low: Hgb, platelets, +/- haptoglobin

General Rules

DIC= elevated PT/INR/PTT/FDPs/D-dimer, low fibrinogen^[1]

TTP/HUS = normal PT/INR/PTT/FDPs/D-dimer/fibrinogen^[1]

Sources

↑ ^1.0 ^1.1 ^1.2 Scully. Marie et al. Guidelines on the diagnosis and management of thrombotic thrombocytopenic purpura and other thrombotic microangiopathies. Br J Haematol. 2012 Aug;158(3):323-35. PDF

Authors:

[guidelines-1] 1.0 ^1.1 ^1.2 Scully. Marie et al. Guidelines on the diagnosis and management of thrombotic thrombocytopenic purpura and other thrombotic microangiopathies. Br J Haematol. 2012 Aug;158(3):323-35. PDF

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