Ordering Recommendation

Use to quantify or monitor paroxysmal nocturnal hemoglobinuria clone size. Preferred initial diagnostic test is Paroxysmal Nocturnal Hemoglobinuria (PNH), High Sensitivity, RBC and WBC (2005006).

New York DOH Approval Status

This test is not New York state approved. Alternative testing that is New York approved is available. See Ordering Recommendations.

Specimen Required

Patient Preparation

New York State Clients: Testing is only approved for the Paroxysmal Nocturnal Hemoglobinuria Panel (ARUP test code 2005006) on whole blood specimens.


Lavender (EDTA), pink (K2EDTA), or green (sodium or lithium heparin).

Specimen Preparation

Transport 4 mL whole blood. (Min: 4 mL)

Storage/Transport Temperature


Unacceptable Conditions

Clotted or hemolyzed specimens.


New York State Clients: Testing is only approved for the Paroxysmal Nocturnal Hemoglobinuria Panel (ARUP test code 2005006) on whole blood specimens.


Ambient: 24 hours; Refrigerated: 72 hours; Frozen: Unacceptable


Quantitative Flow Cytometry




1-3 days

Reference Interval

By report

Interpretive Data

WBC analysis is the most accurate measurement of the PNH clone size. In this high-sensitivity assay, FLAER and CD157 are used as GPI-linked markers; CD15 (PMNs) and CD64 (monocytes) are used as lineage-specific markers. The assay was developed according to published guidelines (Cytometry B Clin. Cytom. 2010; 78:211) and as updated in 2018 (Cytometry B Clin. Cytom. 2018; 94B:49). The lower limit of quantification is 0.02 percent for PNH PMNs (based on 250,000 cells analyzed) and 0.5 percent for PNH monocytes (based on 10,000 cells analyzed). The lower limit of detection for PNH PMNs is 0.008 percent and for PNH monocytes 0.2 percent. For severely pan-cytopenic patients, the WBC assay sensitivity will be much lower. 

The presence of a subclinical PNH population in myelodysplastic bone marrow disorders, such as aplastic anemia or refractory anemia, may correlate with a positive immunotherapeutic response (Blood 2006; 107, 1308-1314).

For initial diagnosis of PNH, order High Sensitivity RBC and WBC Panel (ARUP test code 2005006).

For delineation of RBC Types II and III populations when the RBC clone size is greater than 1 percent, order PNH, High Sensitivity, RBC (ARUP test code 2004366).

Patient Retesting Recommendations: The frequency of testing is dictated by clinical and hematological parameters. Repeat testing is indicated upon any significant change in clinical or laboratory parameters and is suggested at least annually for routine monitoring. In the setting of aplastic anemia, international guidelines recommend screening for PNH at diagnosis, and every 3 to 6 months initially, reducing the frequency of testing if the proportion of GPI-deficient cells has remained stable over an initial two-year period (Int J Lab Hematol 2019;41 Suppl 1:73-81).

This test was developed and its performance characteristics determined by ARUP Laboratories. It has not been cleared or approved by the U.S. Food and Drug Administration. This test was performed in a CLIA-certified laboratory and is intended for clinical purposes.

Compliance Category

Laboratory Developed Test (LDT)


Hotline History


CPT Codes

86356 x4


Component Test Code* Component Chart Name LOINC
2005004 FLAER and CD157-deficient monocytes 77948-8
2005005 FLAER and CD157-deficient neutrophils 77948-8
3005034 Neutrophil PNH Phenotype 93479-4
3005035 Monocyte PNH Phenotype 93479-4
* Component test codes cannot be used to order tests. The information provided here is not sufficient for interface builds; for a complete test mix, please click the sidebar link to access the Interface Map.


  • (CD15, CD64, CD157, FLAER)
  • Eculizumab treatment monitoring assay
  • PI-Linked
Paroxysmal Nocturnal Hemoglobinuria, High Sensitivity, WBC