Tests
1st tests to order
urine dipstick
Test
Almost all patients with classic PNH have episodes of hemoglobinuria during hemolytic episodes.
Result
hemoglobinuria
urine microscopy
Test
Stainable iron in the urine is evidence of intravascular hemolysis.
Result
hemosiderinuria
CBC
Test
Unilineage or multilineage cytopenias may coexist (e.g., leukopenia, thrombocytopenia). Evidence of dysplastic changes in bone marrow and/or peripheral blood may suggest underlying myelodysplasia.
Result
anemia or cytopenia (e.g., granulocytopenia, thrombocytopenia)
reticulocyte count
Test
Assessed to confirm intravascular hemolysis.
Result
increase indicates hemolysis
serum LDH
Test
Other sources of tissue destruction may give the same result; may be resolved by isozyme testing.
Liver damage is characterized by elevated alanine aminotransferase, whereas intravascular hemolysis is not.
Sample must be processed at once to avoid in vitro hemolysis.
Result
increase indicates intravascular hemolysis
unconjugated bilirubin
Test
Assessed to confirm intravascular hemolysis.
Result
elevated
D-dimer
Test
Assesses the risk of thrombosis; elevated D-dimer level suggests an increased risk.
Result
may be elevated
Tests to consider
haptoglobin
Test
Assessed to confirm intravascular hemolysis.
Result
low
flow cytometry for glycosylphosphatidylinositol anchor or anchored proteins
Test
Testing should be done with at least two reagents on RBCs, granulocytes and monocytes.[2]
Result
>1% to 3% of anchor-deficient granulocytes indicates a diagnosis of PNH
fluorescent aerolysin
Test
Done on granulocytes and monocytes. Most sensitive and accurate test.[22]
Result
detects glycosylphosphatidylinositol anchor; >1% to 3% deficient cells indicate PNH
immunotyping
Test
Detects missing proteins on PNH cells.
Result
variable
antiglobulin (Coombs) test
Test
Usually negative except after treatment with complement C5 inhibitors.
Result
detects IgG and C3 on the RBC surface, excludes autoimmune hemolytic anemias
serum iron, serum ferritin
Test
Patients with PNH have unusually large iron losses and may be iron deficient.
Result
low
serum creatinine and BUN
Test
Both acute and chronic renal insufficiency may occur.[10]
Result
variable
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