Lab Test

Paroxysmal Nocturnal Hemoglobinuria Screen

PNH Screening Assay, PI Antigen, PI Linked Antigen, Paroxysmal Nocturnal Hemoglobinuria (PNH) Screening Assay, Flow Cytometry, Paroxysmal Nocturnal Hemoglobinuria (PNH) Screening Assay

Test Codes


Specimen Collection Criteria

Collect: One Lavender-top EDTA tube OR one Green-top Sodium Heparin tube.

A copy of the requisition must be sent with the specimen.

Physician Office/Draw Specimen Preparation

Maintain whole blood at room temperature (20-26°C or 68-78.8°F) prior to transport. Specimens must be received in the Laboratory within 48 hours of collection.

Preparation for Courier Transport

Transport: Whole blood, at room temperature (20-25°C or 68-77°F).

FedEx Shipping Instructions:
Transport 4 mL whole blood at room temperature. Specimen must be received within 48 hours of collection. 

Rejection Criteria

  • Clotted specimens.
  • Specimens received greater than 48 hours post collection are acceptable with the approval of the Flow Cytometry Laboratory manager or pathologist on service.

In-Lab Processing

Maintain at room temperature (20-26°C or 68-78.8°F) prior to testing.


Specimen Stability for Testing:

Room Temperature (20-26°C or 68-78.8°F): 48 hours
Refrigerated (2-8°C or 36-46°F): 48 hours
Frozen (-20°C/-4°F or below): Unacceptable

Specimen Storage in Department Prior to Disposal:

Refrigerated (2-8°C or 36-46°F): 7 days


Royal Oak Flow Cytometry Laboratory


Monday – Saturday.
Specimens must arrive in the Flow Cytometry by 1:00 pm on Saturday to be tested that day.
Results available in 1-2 days.

Reference Range

Normal expression of FLAER and CD14 on monocytes.
Normal expression of FLAER and CD24 on granulocytes.
Normal expression of CD59 on RBCs.

Test Methodology

Immunophenotyping of RBCs, granulocytes, and monocytes by Multiparameter Flow Cytometry.


This assay is reported as normal (absence of a PNH clone) or abnormal (significant PNH clone). If granulocytes or monocytes are abnormal, the percentage of the abnormal clone will be reported. If RBCs are abnormal, the percentage of Type I cells (normal), Type II cells (partial deficiency), and Type III cells (complete deficiency) will be reported.

This test has been validated to a lower limit of detection at 0.01% for Type III red blood cells, granulocytes and monocytes.

Clinical Utility

PNH is a disease that evolves from a hematopoietic stem cell defect in which a somatic mutation of an X-linked gene (PIG-A) results in a partial or absolute deficiency of GPI-linked proteins. Clinical manifestations include chronic intravascular hemolysis, bone marrow failure and life threatening thrombosis. A fluorescein labeled proaerolysin (FLAER) has been identified that binds directly to the GPI anchor and has been shown to be more sensitive at detecting small populations of PNH clones. Monoclonal antibodies to CD59, CD14, and CD24 are also commonly used to examine the presence of these membrane proteins on white blood cells and red blood cells. It has been found that PNH patients express decreased to absent levels of these GPI anchored antigens on monocytes, neutrophils, and RBCs. CD59 expression or absence on RBCs can also provide important information in PNH patients being treated with eculizumab. In patients found to have PNH, the percentage of Type I, II, and III RBCs, as well as the percentages of granulocyte and monocyte PNH clones will be reported so that patients can be followed more effectively.

CPT Codes

88184x1, 88185x3, 88187 – Interpretation 2-8 markers.


Last Updated


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This directory currently reflects information only for specimens collected and/or processed at the
Farmington Hills, Grosse Pointe, Royal Oak, and Troy campuses.