A rare, acquired hemolytic stem cell disorder.
PNH is an uncommon disorder of unknown frequency both in the
United States and worldwide. It is estimated that it is observed 5-10 times less than
with aplastic anemia. It may be more frequent in Southeast Asia and the Far East. The
disease process is insidious and has a chronic course, with a median survival of about 10
years. The morbidity is influenced by the importance of the hemolysis, bone marrow
failure, and thrombophilia. Men and women are affected equally and the onset begins in
childhood (<2 years of age) to adulthood (as old as 85 years of age). Other complications include
infections and thrombosis.
Hemopoietic stem cell disorder leads to the
production of defective platelets, granulocytes, and RBCs. The hemolysis
might be triggered by acidosis during sleep. The RBCs have increased
sensitivity to complement-mediated hemolysis as a result of deficient
decay-accelerated factor. Platelets, too, are more sensitive to complement
Laboratory diagnosis is based on the Ham test, which
mixes affected RBCs with slightly acidified, but otherwise normal, serum.
This leads to complement-mediated hemolysis.
Chronic hemolysis, anemia, pancytopenia,
potentially life-threatening thrombosis secondary to platelet activation,
low serum haptoglobin, elevated lactate dehydrogenase, hemosiderinuria,
intermittent hemoglobinuria, especially when urine is concentrated, and
normal peripheral smear, ± steroids.
Check hematocrit, anticipate need
for transfusion. Check prothrombin time if the administration of
anticoagulant is considered against thrombosis.
Maintain oxygen-carrying capacity. Avoid
regional anesthesia if the patient is anticoagulated or if thrombocytopenia is present.
Steroid supplementation is highly recommended.
Kjaer K, Comerford M, Godalla F: General anesthesia for cesarean delivery in a patient
with paroxysmal nocturnal hemoglobinuria and thrombocytopenia. Anesth Analog
Tabbara IA: Hemolytic anemias diagnosis and management. Med Clin North Am 76(3);649,