The risk for thromboembolic disease is increased in some patients with paroxysmal nocturnal hemoglobinuria (PNH). For these patients the thrombi may be associated with significant morbidity and mortality.


Thrombi may be arterial or venous.


Sites of thrombosis:

(1) dermal blood vessels

(2) hepatic vein (Budd-Chiari syndrome)

(3) portal vein

(4) mesenteric vein

(5) splenic vein

(6) cerebral sinus (sagittal, cavernous)

(7) deep vein thrombosis in extremities

(8) inferior vena cava

(9) coronary arteries

(10) cerebral arteries

(11) renal vein


Clinical presentations:

(1) recurrent stroke

(2) pulmonary embolism

(3) acute myocardial infarction

(4) thrombosis during pregnancy


The risk of thrombosis is greater with higher percentage of PNH cells (> 50% of granulocytes).


Some patients treated with heparin may develop heparin-induced thrombocytopenia with thrombosis.


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