Ham’s Test, Blood

Paroxysmal nocturnal Hemoglobinuria (PNH) is most common in men in their 20s, but it occurs in both sexes and at any age. It is an acquired genetic mutation resulting in a membrane defect in stem cells and their progeny, including RBCs, WBCs, and platelets. It results in unusual sensitivity to normal C3 in the plasma, leading to ongoing intravascular hemolysis of RBCs and diminished marrow production of WBCs and platelets. The defect is a missing glycosylphosphatidyl- inositol anchor for membrane proteins caused by an abnormality of the PIG-A gene, which is located on the X chromosome. Protracted urinary Hemoglobin loss may result in iron deficiency. Patients are strongly predisposed to both venous and arterial thrombi, including the Budd-Chiari syndrome. Thrombi are commonly fatal. Some patients with PNH develop aplastic anemia, and some with aplastic anemia develop PNH.

The diagnosis of PNH requires flow cytometry, although the acid hemolysis test (Ham’s test) is still valid. The red cells are tested for resistance to lysis during incubation with acidified fresh serum. Lowering of pH results in complement lysis of red cells with the PNH defect. PNH occurs in 55-65% of cases of myeloid metaplasia and primary myelofibrosis. Hemosiderin in urine should also be measured.

2 ml EDTA Whole Blood Room Temperature

Sample must be processed within 24 Hrs of collection.

Negative