Test Catalog

Test Id : PLINK

Paroxysmal Nocturnal Hemoglobinuria, PI-Linked Antigen, Blood

Useful For
Suggests clinical disorders or settings where the test may be helpful

Screening for and confirming the diagnosis of paroxysmal nocturnal hemoglobinuria (PNH)


Monitoring patients with PNH

Additional Tests
Lists tests that are always performed, at an additional charge, with the initial tests.

Test Id Reporting Name Available Separately Always Performed
FCIMS Flow Cytometry Interp, 9-15 Markers No, (Bill Only) Yes

Method Name
A short description of the method used to perform the test


NY State Available
Indicates the status of NY State approval and if the test is orderable for NY State clients.


Reporting Name
Lists a shorter or abbreviated version of the Published Name for a test

PNH, PI-Linked AG, B

Lists additional common names for a test, as an aid in searching

Acid Hemolysin




GPI-Linked Antigen

Ham-Crosby Sugar-Water Test, Blood

Hemolytic Anemia

Paroxysmal Nocturnal Hemoglobinuria (PNH)

PI Linked Antigen

Sucrose Analysis

Sucrose Fragility

Sucrose Hemolysis

Sugar Water PNH Screen

Sugar Water Test, Ham-Crosby, Blood

Specimen Type
Describes the specimen type validated for testing

Whole blood

Specimen Required
Defines the optimal specimen required to perform the test and the preferred volume to complete testing

Specimen must arrive within 72 hours of collection.



Preferred: Yellow top (ACD)

Acceptable: Lavender top (EDTA)

Specimen Volume: 2.6 mL

Collection Instructions: Send whole blood specimen in original tube. Do not aliquot.


Specimen Minimum Volume
Defines the amount of sample necessary to provide a clinically relevant result as determined by the testing laboratory. The minimum volume is sufficient for one attempt at testing.

1 mL

Reject Due To
Identifies specimen types and conditions that may cause the specimen to be rejected

Gross hemolysis Reject

Specimen Stability Information
Provides a description of the temperatures required to transport a specimen to the performing laboratory, alternate acceptable temperatures are also included

Specimen Type Temperature Time Special Container
Whole blood Ambient (preferred) 72 hours
Refrigerated 72 hours

Useful For
Suggests clinical disorders or settings where the test may be helpful

Screening for and confirming the diagnosis of paroxysmal nocturnal hemoglobinuria (PNH)


Monitoring patients with PNH

Clinical Information
Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

Paroxysmal nocturnal hemoglobinuria (PNH) is an acquired hematologic disorder characterized by nocturnal hemoglobinuria, chronic hemolytic anemia, thrombosis, pancytopenia, and, in some patients, acute or chronic myeloid malignancies.


PNH appears to be a hematopoietic stem cell disorder that affects erythroid, granulocytic, and megakaryocytic cell lines. The abnormal cells in PNH have been shown to lack glycosylphosphatidylinositol (GPI)-linked proteins in erythroid, granulocytic, megakaryocytic, and, in some instances, lymphoid cells. Variants in the phosphatidylinositol glycan A gene, PIGA, have been identified consistently in patients with PNH, thus confirming the biological defect in this disorder.


A flow cytometric-based assay can detect the presence or absence of these GPI-linked proteins in granulocytes, monocytes, erythrocytes, and lymphocytes, thus avoiding the problems associated with red blood cell (RBC)-based diagnostic methods (Ham test) in which recent hemolytic episodes or recent transfusions can give false-negative results. A partial list of known GPI-linked proteins includes CD14, CD16, CD24, CD55, CD56, CD58, CD59, C8-binding protein, alkaline phosphatase, acetylcholine esterase, and a variety of high frequency human blood antigens. In addition, fluorescent aerolysin binds directly to the GPI anchor and can be used to evaluate the expression of the GPI linkage.


In-house studies, as well as others in the literature, have shown that flow cytometry-based assays will detect all Ham-positive PNH cases, as well as some Ham-negative PNH cases. This assay replaces the sugar water test and the Ham test for the evaluation of patients with possible PNH.


Patients with PNH should be transfused with ABO-specific RBCs, which do not need to be washed. If, for some reason, they need to receive non-ABO type-specific (type O) cells, these RBC units should be washed. Since recipient antibodies to granulocyte antigens can trigger hemolytic episodes in PNH, if they have such antibodies these patients should receive leukoreduced RBCs and platelets.

Reference Values
Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.

An interpretive report will be provided. 



PNH RBC-Partial Antigen loss: 0.00-0.99%

PNH RBC-Complete Antigen loss: 0.00-0.01%

PNH Granulocytes: 0.00-0.01%

PNH Monocytes: 0.00-0.05%

Provides information to assist in interpretation of the test results

Individuals with paroxysmal nocturnal hemoglobinuria (PNH) have absent or decreased expression of all the glycosylphosphatidylinositol (GPI)-linked antigens and fluorescent aerolysin (FLAER) on peripheral blood cells derived from the PNH clone.


Recent data showed that small PNH clones can be detected in a relatively high percentage of cases of aplastic anemia and myelodysplastic syndrome. While the significance of this finding is still uncertain, it appears that these patients may benefit from immunosuppressive therapy.


This test incorporates a sophisticated technique of separating different cell populations using gating on antigen-positive cells, as well as the sensitivity to enable detection of small PNH clones. In addition, this test detects a partial loss of CD59 on type II red blood cells (RBC). Patients with large proportion of type II RBC are unlikely to show high levels of hemolysis, unlike patients with complete loss of GPI-linked proteins (predominantly type III cells). While PNH is a disorder of hematopoietic stem cells and all lineages are affected, the percentage of affected cells can differ between lineages, most commonly due to hemolysis and/or transfusion.


Individuals without PNH have normal expression of FLAER (neutrophils and monocytes) and normal expression of all GPI-linked antigens-CD14 (monocytes), CD16 (neutrophils and NK cells), CD24 (neutrophils), and CD59 (RBC).

Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

The sugar water test and the Ham test are no longer recommended for the evaluation of patients with possible paroxysmal nocturnal hemoglobinuria.


Recent transfusion can decrease the sensitivity of this test and interfere with accuracy.

Clinical Reference
Recommendations for in-depth reading of a clinical nature

1. Richards SJ, Hill A, Hillman P: Recent advances in the diagnosis, monitoring and management of patients with paroxysmal nocturnal hemoglobinuria. Cytometry B Clin Cytom. 2007 Sep;72(5):291-298

2. Sutherland DR, Illingworth A, Marinov I, et al: ICCS/ESCCA consensus guidelines to detect GPI-deficient cells in paroxysmal nocturnal hemoglobinuria (PNH) and related disorders part 2 - reagent selection and assay optimization for high-sensitivity testing. Cytometry B Clin Cytom. 2018 Jan;94(1):23-48. doi: 10.1002/cyto.b.21610

3. Illingworth A, Marinov I, Sutherland DR, Wagner-Ballon O, DelVecchio L: ICCS/ESCCA consensus guidelines to detect GPI-deficient cells in paroxysmal nocturnal hemoglobinuria (PNH) and related disorders part 3 - data analysis, reporting and case studies. Cytometry B Clin Cytom. 2018 Jan;94(1):49-66. doi: 10.1002/cyto.b.21609

4. Oldaker T, Whitby L, Saber M, Holden J, Wallace PK, Litwin V: ICCS/ESCCA consensus guidelines to detect GPI-deficient cells in paroxysmal nocturnal hemoglobinuria (PNH) and related disorders part 4 - assay validation and quality assurance. Cytometry B Clin Cytom. 2018 Jan;94(1):67-81. doi: 10.1002/cyto.b.21615

5. Dezern AE, Borowitz MJ: ICCS/ESCCA consensus guidelines to detect GPI-deficient cells in paroxysmal nocturnal hemoglobinuria (PNH) and related disorders part 1 - clinical utility. Cytometry B Clin Cytom. 2018 Jan;94(1):16-22. doi: 10.1002/cyto.b.21608

6. Illingworth AJ, Marinov I, Sutherland DR: Sensitive and accurate identification of PNH clones based on ICCS/ESCCA PNH Consensus Guidelines-A summary. Int J Lab Hematol. 2019 May;41 Suppl 1:73-81. doi: 10.1111/ijlh.13011

7. Seth N, Mahajan V, Kedia S, Sutar A, Sehgal K. Utility of FLAER and CD157 in a five-color single-tube high sensitivity assay, for diagnosis of Paroxysmal Nocturnal Hemoglobinuria (PNH)-A standalone flow cytometry laboratory experience. Int J Lab Hematol. 2021 Apr;43(2):259-265. doi: 10.1111/ijlh.13366

8. Payne D, Johansson U, Bloxham D, et al: Inter-laboratory validation of a harmonized PNH flow cytometry assay. Cytometry B Clin Cytom. 2018 Sep;94(5):580-587. doi: 10.1002/cyto.b.21726

9. Sutherland DR, Ortiz F, Quest G, et al: High-sensitivity 5-, 6-, and 7-color PNH WBC assays for both Canto II and Navios platforms. Cytometry B Clin Cytom. 2018 Jul;94(4):637-651. doi: 10.1002/cyto.b.21626

Method Description
Describes how the test is performed and provides a method-specific reference

Flow cytometric immunophenotyping of peripheral blood (white blood cells [WBC] and red blood cells [RBC]) is performed using the following antibodies:


RBC: CD235a, CD59 

WBC: CD14, CD15, CD16, CD24, CD33, CD45, and FLAER


This assay evaluates the presence or absence of glycosylphosphatidylinositol (GPI)-linked proteins using monoclonal antibodies directed against CD235, CD33, and CD15 to isolate different cell lineages. GPI-linked proteins that are checked within different lineages include CD14 for monocytes, CD's 16 and 24 for granulocytes, and CD59 for RBC. Fluorescent aerolysin (FLAER), a fluorescently labeled inactive variant of the protein aerolysin, binds selectively to GPI anchors and is evaluated for presence or absence of expression on WBC. In addition, this test will detect a partial loss of CD59 on RBC (type II RBC).


Individuals without paroxysmal nocturnal hemoglobinuria have normal expression of all GPI-linked antigens on peripheral blood and leukocytes and erythrocytes.(Devalet B, Mullier F, Chatelain B, Dogné JM, Chatelain C: Pathophysiology, diagnosis, and treatment of paroxysmal nocturnal hemoglobinuria: a review. Eur J Haematol. 2015 Sep;95(3):190-198. doi: 10.1111/ejh.12543)

PDF Report
Indicates whether the report includes an additional document with charts, images or other enriched information


Day(s) Performed
Outlines the days the test is performed. This field reflects the day that the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time before the test is performed. Some tests are listed as continuously performed, which means that assays are performed multiple times during the day.

Monday through Friday

Report Available
The interval of time (receipt of sample at Mayo Clinic Laboratories to results available) taking into account standard setup days and weekends. The first day is the time that it typically takes for a result to be available. The last day is the time it might take, accounting for any necessary repeated testing.

1 to 2 days

Specimen Retention Time
Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded

14 days

Performing Laboratory Location
Indicates the location of the laboratory that performs the test


Several factors determine the fee charged to perform a test. Contact your U.S. or International Regional Manager for information about establishing a fee schedule or to learn more about resources to optimize test selection.

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  • Clients without access to Test Prices can contact Customer Service 24 hours a day, seven days a week.
  • Prospective clients should contact their account representative. For assistance, contact Customer Service.

Test Classification
Provides information regarding the medical device classification for laboratory test kits and reagents. Tests may be classified as cleared or approved by the US Food and Drug Administration (FDA) and used per manufacturer instructions, or as products that do not undergo full FDA review and approval, and are then labeled as an Analyte Specific Reagent (ASR) product.

This test was developed using an analyte specific reagent. Its performance characteristics were determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the US Food and Drug Administration.

CPT Code Information
Provides guidance in determining the appropriate Current Procedural Terminology (CPT) code(s) information for each test or profile. The listed CPT codes reflect Mayo Clinic Laboratories interpretation of CPT coding requirements. It is the responsibility of each laboratory to determine correct CPT codes to use for billing.

CPT codes are provided by the performing laboratory.

88184-Flow cytometry, RBC x 1

88184-Flow cytometry, WBC x 1

88185-Flow cytometry, additional marker (each), RBC x 1

88185-Flow cytometry, additional marker (each), WBC x 6

88188-Flow Cytometry Interpretation, 9-15 Markers x 1

LOINC® Information
Provides guidance in determining the Logical Observation Identifiers Names and Codes (LOINC) values for the order and results codes of this test. LOINC values are provided by the performing laboratory.

Test Id Test Order Name Order LOINC Value
PLINK PNH, PI-Linked AG, B 90735-2
Result Id Test Result Name Result LOINC Value
Applies only to results expressed in units of measure originally reported by the performing laboratory. These values do not apply to results that are converted to other units of measure.
CK079 Interpretation 90739-4
CK080 PNH RBC-Partial Ag Loss 33662-8
CK081 PNH RBC-Complete Ag Loss 90738-6
CK082 PNH Granulocytes 90737-8
CK083 PNH Monocytes 90736-0

Test Setup Resources

Setup Files
Test setup information contains test file definition details to support order and result interfacing between Mayo Clinic Laboratories and your Laboratory Information System.

Excel | Pdf

Sample Reports
Normal and Abnormal sample reports are provided as references for report appearance.

Normal Reports | Abnormal Reports

SI Sample Reports
International System (SI) of Unit reports are provided for a limited number of tests. These reports are intended for international account use and are only available through MayoLINK accounts that have been defined to receive them.

SI Normal Reports | SI Abnormal Reports