Paroxysmal Nocturnal Hemoglobinuria, PI-Linked Antigen, Blood

Casandra

Casandra Test Code MC66454Version 1 (DRAFT)

Performing Lab

Lab Mayo Clinic LabLab Test ID PLINKCPT Codes 88184, 88185, 88188

Paroxysmal Nocturnal Hemoglobinuria, PI-Linked Antigen, Blood

Clinical Use

Use

This test is useful for screening and confirming the diagnosis of paroxysmal nocturnal hemoglobinuria (PNH) and for monitoring patients with PNH. PNH is an acquired hematologic disorder characterized by nocturnal hemoglobinuria, chronic hemolytic anemia, thrombosis, pancytopenia, and acute or chronic myeloid malignancies in some patients. It is a stem cell disorder affecting various blood cell lines, resulting in a deficiency of GPI-linked proteins. Variants in the PIGA gene are commonly identified in PNH patients, confirming the biological defect. Flow cytometry assays detect GPI-linked protein absence in blood cells, providing a more reliable diagnosis by avoiding the issues of RBC-based diagnostic methods.

Special Instructions

Ensure that specimens are collected without prior transfusion if possible, to avoid decreased test sensitivity. Specimens must arrive within 72 hours of collection to ensure validity of results. Complete appropriate forms if not ordering electronically. Transport specimens under appropriate conditions as outlined in the shipping instructions.

Limitations

This assay replaces the sugar water test and the Ham test for evaluating PNH, providing more reliability in detecting all Ham-positive PNH cases and some Ham-negative cases. Recent hemolytic episodes or transfusions may interfere with RBC-based diagnosis, leading to false negatives. While PNH affects stem cells, the percentage of affected cells can vary between lineages due to hemolysis and/or transfusion. It is important to note that recent transfusions can decrease the sensitivity of the test and interfere with accuracy.

Test Details

New York Approved