Platelet Antibody, Serum
NY State Approved Indicates the status of NY State approval and if the test is orderable for NY State clients.
Evaluating cases of immune platelet refractoriness, post-transfusion purpura, or neonatal alloimmune thrombocytopenic purpura
Enzyme-Linked Immunoabsorbent Assay (ELISA)
Reporting Name A shorter/abbreviated version of the Published Name for a test; an abbreviated test name
Platelet Ab, S
Circulating Platelet Antibody
Indirect Platelet Antibody
Circulating Platelet Antibody
Indirect Platelet Antibody
Specimen Type Describes the specimen type needed for testing
Specimen Required Defines the optimal specimen. This field describes the type of specimen required to perform the test and the preferred volume to complete testing. The volume allows automated processing, fastest throughput and, when indicated, repeat or reflex testing.
Collection Container/Tube: Red top
Submission Container/Tube: Plastic vial
Specimen Volume: 1.5 mL
Specimen Minimum Volume Defines the amount of specimen required to perform an assay once, including instrument and container dead space. Submitting the minimum specimen volume makes it impossible to repeat the test or perform confirmatory or perform reflex testing. In some situations, a minimum specimen volume may result in a QNS (quantity not sufficient) result, requiring a second specimen to be collected.
Mild reject; Gross reject
Serum gel tube
Specimen Stability Information Provides a description of the temperatures required to transport a specimen to the laboratory. Alternate acceptable temperature(s) are also included.
|Serum Red||Frozen (preferred)||365 days|
Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test
Platelet antibodies may be allo- or autoantibodies and may be directed to a wide range of antigenic "targets" carried on platelet cytoplasmic membranes.
Platelet alloantibodies are involved in several clinical situations such as alloimmune platelet refractoriness (APR), neonatal alloimmune thrombocytopenic purpura (NATP), and posttransfusion purpura (PTP). In these settings, the antibodies, usually HLA Class I in the case of APR, and platelet-specific antibodies eg, HPA-1a (PLA1) in the case of NATP or PTP, are found in the patient's plasma and are detected by tests performed on serum.
In contrast, conditions such as idiopathic thrombocytopenic purpura (ITP), systemic lupus erythematosus (SLE), or sepsis are associated with the presence of excessive platelet associated immunoglobulin usually IgG. Testing for cell bound platelet antibody is indicated for the diagnosis of these autoimmune conditions. In some cases of ITP, platelet antibodies can also be found in the patient's serum but with less frequently than cell bound antibody.
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.
Presence of reactivity to some glycoproteins has no clearly established clinical significance.
Results are based on clinical situation as well as test results.
Serum platelet antibody testing by solid-phase enzyme-linked immunoassay offers more than a positive/negative result. When the patient's serum is positive, the specific platelet glycoprotein will be identified as well as the probable specificity. The platelet glycoproteins reported are: IIb/IIIa, Ia/IIa, GPIb/IX. Specificities include the following: HPA-1a (PL[a1]), HPA-1b (PL[a2]), HPA-3a (BAK[a]/LEK[a]), HPA-3b (BAK[b]), HPA-5b (Br[a]), HPA-5a (Br[b]). Those specificities listed in parenthesis refer to old nomenclature. In addition, this assay screens for HLA Class I antibodies, but specificity is not determined.
Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances
No significant cautionary statements
Our method (solid-phase enzyme immunoassay [SPEIA]) uses purified platelet membrane glycoproteins as "targets" rather than intact platelets and this provides a simple "panel" of target antigens.
We have performed extensive parallel studies of SPEIA and indirect immunofluorescence methods using monospecific, well-characterized reagent grade HLA Class I antibodies and antibodies to the most commonly encountered, clinically relevant platelet specific antigen (HPA-1a [PLA1]). These studies were performed using dilutions of the sera to determine relative sensitivity of the 2 methods. The results clearly indicate greater sensitivity of the SPEIA method for every 1 of 16 antibodies tested.
The HLA antibodies were also tested in parallel by complement dependent cytotoxicity (CDC), the universal standard method for testing for HLA antibodies. The SPEIA method was similarly more sensitive than CDC. No false-positive reactions were seen with the SPEIA method in testing these well-defined alloantibodies.
Although the detection of platelet autoantibodies is better accomplished by direct cell bound methods, such autoantibodies are sometimes detected in serum. We compared the SPEIA and indirect immunofluorescence tests in parallel using sera from patients thought to have autoimmune thrombocytopenia. The results indicated comparable sensitivity of the 2 serum tests and, as expected, greater sensitivity of the direct cell bound test run in parallel with the 2 serum tests. Interestingly, the reactivity patterns seen in the SPEIA suggested that where antibodies were detectable in idiopathic thrombocytopenic purpura patients, they were more frequently directed to glycoprotein IIb/IIIa as has been previously reported.
In summary, for the detection of platelet alloantibodies, the SPEIA method is more sensitive than the indirect immunofluorescence method. In addition, it permits discrimination of the reactivity patterns against the most commonly encountered platelet antigens. The SPEIA method is also a more rapid and automatable method which reduces test turnaround time from 8 hours to 4 hours.
Clinical Reference Provides recommendations for further in-depth reading of a clinical nature
1. Kiefel V, Santoso S, Weisheit M, et al: Monoclonal antibody-specific immobilization of platelet antigens (MAIPA): A new tool for the identification of platelet-reactive antibodies. Blood 1987;70:1722-1726
2. Moore SB, DeGoey SR: Serum platelet antibody testing: evaluation of solid-phase enzyme immunoassay and comparison with indirect immunofluorescence. Am J Clin Pathol 1998;109:190-195
Method Description Describes how the test is performed and provides a method-specific reference
Solid-phase enzyme immunoassay (SPEIA) uses purified platelet membrane glycoproteins as "targets" rather than intact platelets and this provides a simple "panel" of target antigens. These purified glycoproteins are permanently affixed to the interior of concave wells in plastic trays. The attachment of patient antibodies to these glycoproteins is detected by the addition of a second stage antihuman globulin reagent which is enzyme tagged. The addition of enzyme substrate is followed by a visible color change which permits rapid visual reading of the tray or automatable reading. (Moore SB, DeGoey SR: Serum platelet antibody testing: evaluation of solid-phase enzyme immunoassay and comparison with indirect immunofluorescence. Am J Clin Pathol:1998;109:190-195)
Day(s) and Time(s) Test Performed Outlines the days and times the test is performed. This field reflects the day and time the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time required before the test is performed. Some tests are listed as continuously performed, which means assays are performed several times during the day.
Monday through Friday; 7:30 a,m.-5:00 p.m.
Saturday; 10:00 a.m.-6:00 p.m
Analytic Time Defines the amount of time it takes the laboratory to setup and perform the test. This is defined in number of days. The shortest interval of time expressed is "same day/1 day," which means the results may be available the same day that the sample is received in the testing laboratory. One day means results are available 1 day after the sample is received in the laboratory.
Maximum Laboratory Time Defines the maximum time from specimen receipt at Mayo Medical Laboratories until the release of the test result
Specimen Retention Time Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded
Performing Laboratory Location The location of the laboratory that performs the test
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's instructions, or as products that do not undergo full FDA review and approval, and are then labeled as an Analyte Specific Reagent (ASR), Investigation Use Only (IUO) product, or a Research Use Only (RUO) product.
This test has been modified from the manufacturer's instructions. Its performance characteristics were determined by Mayo Clinic in a manner consistent with CLIA requirements.
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 Medical Laboratories interpretation of CPT coding requirements. It is the responsibility of each laboratory to determine correct CPT codes to use for billing.
LOINC® Code Information Provides guidance in determining the Logical Observation Identifiers Names and Codes (LOINC) values for the result codes returned for this test or profile.
|Result ID||Reporting Name||LOINC Code|
|PL_AB||Platelet Ab, S||24375-8|