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Platelet Function Analysis

PFA, Platelet Function Evaluation, Platelet Function Screen

Test Codes

EPIC: LAB1231132

Department

Coagulation

Instructions

This test is available only to patients drawn on the Dearborn, Grosse Pointe, Royal Oak, Trenton and Troy Hospital campuses.

Specimen Collection Criteria

Collect: Two Light Blue-top 3.2% Sodium Citrate tubes.

• TUBES MUST BE FULL.
• Venipuncture should be performed using a 21G or larger needle (20G or 19G). Use of a butterfly collection device is not recommended.
• Tubes must be HAND-DELIVERED to the Coagulation Laboratory immediately. Do NOT send through the pneumatic tube system.

Preparation for Courier Transport

Transport: Whole blood at room temperature (20-26°C or 68-78.8°F).

Rejection Criteria

• Specimens collected in Serum Separator (SST) or Heparin tubes.
• Specimens collected at sites other than Dearborn, Grosse Pointe, Royal Oak, Trenton and Troy Hospital campuses.
• Glass tubes and 3.8% Sodium Citrate tubes.
• Specimens that are clotted or grossly hemolyzed.
• Inappropriate specimen volume.
• Specimens received in the Laboratory more than 1 hour past the time of collection.

Inpatient Specimen Preparation

Hand-deliver specimens to the Laboratory immediately after collection DO NOT use the pneumatic tube system.

In-Lab Processing

Do not refrigerate or freeze specimens. Do not centrifuge. Specimens must be analyzed within 3 hours of collection.

Storage

Specimen Stability for Testing:

Room Temperature (20-26°C or 68-78.8°F): 3 hours
Refrigerated (2-8°C or 36-46°F): Unacceptable
Frozen (-20°C/-4°F or below): Unacceptable

Specimen Storage in Department Prior to Disposal:

Room Temperature (20-26 C or 68-78.8 F): 5 days
Refrigerated (2-8°C or 36-46°F): 5 days

Laboratory

Dearborn Hematology Laboratory
Grosse Pointe Hematology/Coagulation Laboratory
Royal Oak Coagulation Laboratory
Trenton Hematology Laboratory
Troy Hematology/Coagulation Laboratory

Performed

Sunday – Saturday, 24 hours a day.
Results available within 3 hours of receipt in the Laboratory.

Reference Range

Collagen/Epinephrine: Less than or equal to 160 seconds.
Collagen/ADP: Less than or equal to 106 seconds.

Children greater than two years of age have been reported to have closure times similar to adults.

Test Methodology

Artificial Wound Model which measures Closure Time (Siemens PFA-100 Analyzer).

Interpretation

The end point of the assay is closure time. Prolongation of closure times with both ADP and Epi cartridges indicates a defect in platelet function or Von Willebrand Disease (VWD). Prolongation of the Coll-Epi closure time with normal or near normal Coll-ADP closure time is characteristic of aspirin. Ticlopidine (Ticlid) and clopidogrel (Plavix) without concurrent apsirin do not affect the PFA-100.

	Coll-ADP	Coll-Epi
Platelet defects	Increased	Increased
VWD	Increased	Increased
Aspirin	Near Normal	Increased

A normal PFA-100 result does not completely exclude platelet dyfunction as it lacks sensitivity to some congenital defects and anti-platelet drugs. If there is substansive bleeding history or further clinical suspicion of a bleeding disorder, consider platelet aggregation studies for further evaluation. Platelet aggregation studies can be arranged by calling the Appointment Center. 

Limitations:

• Microthrombi in the sample or particulates introduced into the sample from the environment could adversely affect the test results.
• The medication history of the patient should be reviewed as many medications are known to affect platelet function.
• Results will be affected by low hematocrits (less than 35) or decreased platelet counts (less than 150,000).
• Certain fatty acids and lipids found in various human diets are known to inhibit platelet function. Physicians may wish to advise patients to refrain from fatty foods prior to testing.
• Hemolyzed specimens may interfere with this assay by reduction in hematocrit or the release of ADP.

Clinical Utility

This assay provides an indication of platelet function. This assay is a screening test for platelet function defects, von Willebrand disease, and aspirin-induced platelet dysfunction. Results should be evaluated in conjunction with clinical history and other laboratory findings (e.g. platelet aggregation).

CPT Codes

Per agonist: 85576 x2

LOINC:
ADP: 24472-3
EPI: 24471-5

Contacts

Last Updated

10/21/2024