Which of the following statements concerning PNH is the most accurate for this patient?
A 45-year-old white woman presents for the first time to your clinic after seeing several doctors for vague complaints of abdominal and back pain. A thorough workup to this point has been unrevealing, aside from a mild anemia and indirect hyperbilirubinemia. Her past medical history is significant for recurrent left leg deep vein thrombosis, for which she is currently on warfarin. You suspect and confirm the diagnosis of paroxysmal nocturnal¬†hemoglobinuria (PNH) and would like to educate her about the disease.
A. PNH is caused by the loss of a cell surface¬≠anchoring membrane, making erythrocytes more susceptible to complement activation. B. In cases that result in severe anemia, transfusion of packed RBCs is recommended. C. Although PNH frequently causes thrombosis, it rarely results in fatal events. D. The median survival of patients with PNH is 20 years.
Pnh is caused by the loss of a cell surface‚≠anchoring membrane, making erythrocytes more susceptible to complement activation.-pnh is a somatic clonal disorder of hematopoietic stem cells. pnh involves the pig-a gene, which maps to the short arm of the x chromosome. the mutation results in a deficiency of the membrane-anchoring protein phosphatidylinositol glycan class a, making erythrocytes more susceptible to complement activation. normal human erythrocytes, and probably platelets and neutrophils, modulate complement attack by at least three gpi membrane-bound proteins: daf (cd55), c8-binding protein (c8bp), and mirl (cd59). in the absence of the gpi anchor, all of the proteins that use this membrane anchor will be variably deficient in the blood cells of persons with pnh. classically, acute episodes of intravascular hemolysis are superimposed on a background of chronic hemolysis. the patient typically notes hemoglobinuria on voiding after sleep. recurrent venous occlusions lead to pulmonary embolism and hepatic and mesenteric vein thrombosis, possibly resulting from release of procoagulant microparticles derived from platelets. a literature review found that thrombotic events accounted for 22% of deaths in patients with pnh. occasionally, pnh patients with thrombosis are mistakenly thought to have psychosomatic disorders because they complain of recurrent severe pain in the abdomen and back that has no obvious cause or with impotence. in pnh, the anemia is occasionally so severe (hemoglobin level < 8 g/dl) that the patient needs transfusions regularly; therefore, the choice of transfusion component is critical. it is believed that infusion of blood products containing complement may enhance hemolysis. infusion of donor white blood cells, which are ordinarily present in a unit of packed rbcs, into a human leukocyte antigen≠immunized recipient may provide the antigen-antibody reaction that activates complement by the classical pathway. in such a case, the use of special leukocyte-poor units may be helpful. a study of 80 patients with pnh indicated that the median survival was 10 years.