Microangiopathic hemolytic anemia

Background

• A 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

Clinical Features

• Clinical features + heme labs with red blood cell fragments or schistocytes.
• May have bleeding and thrombosis

Differential Diagnosis

Microangiopathic Hemolytic Anemia (MAHA)

• Disseminated Intravascular Coagulation (DIC)
• Thrombotic Thrombocytopenic Purpura (TTP)
• Hemolytic Uremic Syndrome (HUS)
• HELLP syndrome
• Heparin-Induced Thrombocytopenia (HIT)
• Hereditary spherocytosis
• Paroxysmal nocturnal hemoglobinuria (PNH)
• Malignant hypertension
• Scleroderma
• Antiphospholipid Syndrome (APS)
• Other medical causes: 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 with mechanical, more common at aortic valve), LVAD, TIPS, coil embolization, patched AV shunt, AVM

Diagnosis

• 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

• TTP/HUS = normal PT/INR/PTT/FDPs/D-dimer/fibrinogen

See Also

• Anemia
• Malignant hypertension, HELLP, Antiphospholipid Syndrome (APS), Paroxysmal Nocturnal Hemoglobinuria (PNH)