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
• May have bleeding and thrombosis

DDx

• Most common causes: DIC, TTP, HUS
• Other medical causes: malignant hypertension, HELLP, antiphospholipid syndrome, scleroderma, PNH, malignancy, renal allograft rejection, vasculitides like polyarteritis nodosa and Wegener's granulomatosis
• Drugs: chemotherapy; Plavix (clopidogrel) 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

• All MAHAs =
  • Schistocytes
  • High: +/- LDH and bili
  • Low: Hgb, platelets, +/- haptoglobin

• DIC = elevated PT/INR/PTT/FDPs/D-dimer, low fibrinogen

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

See Also

• DIC, TTP, HUS
• Malignant hypertension, HELLP, antiphospholipid syndrome, PNH
• HIT