Geisinger Medical Laboratories Test Catalog

Order Display Name: Geisinger Epic Procedure Code Or ID CPT Code:  


Geisinger Epic Procedure Code: LAB2858             Geisinger Epic ID: 21449

Specimen type:
Platelet-rich plasma
Preferred collection container:
Alternate Collection Container:
4.5 mL blue top (3.2% sodium citrate) tube
Specimen required:
18 mL (6 x 3 mL tubes) whole blood aliquot for a single study.
Special notes:
  • Test must be scheduled and collected at GMC (Danville, PA). To schedule please call the Hematology/Coagulation Laboratory at 570-271-6323.
  • Patient’s platelet count should be >50,000/mm3 prior to testing. Patient should not be receiving aspirin containing medications, non-steroidal anti-inflammatory drugs or cardiovascular medications such as dipyridamole within two (2) weeks prior to testing.
  • If the patient’s hematocrit (HCT) is >55%, the volume of anticoagulant in the tube must be adjusted. Contact a performing location for sodium citrate adjusted tubes.
  • Avoid prolonged tourniquet time (< 1 minute) and hemolysis during collection as this will alter results.
  • Blood may be drawn from an indwelling catheter or vascular access device. Draw sample from a lumen that has not been heparinized or flush the line with 5 mL of saline and discard/use first 5-10 mL of blood for other purposes.
  • Tubes should be >90% filled.
  • Immediately mix gently after collection by inverting the tube end over end 5 to 10 times. Avoid vigorous mixing or additional inversion. Observe for the presence of clots or hemolysis and recollect if observed.

Specimen processing instructions:
Do NOT process. Hand-deliver to the Coagulation Laboratory 
Transport temperature:
Room temperature.
Specimen stability:
Room temperature: 4 hours.
Rejection criteria:
Clotted, severely hemolyzed/lipemic/icteric, improperly filled tubes, improper anticoagulant ratio (HCT >55% and citrate not adjusted), refrigerated/frozen specimens, stability exceeded, or platelet count <50,000/mm3.

Reference interval:
ADP 10 uM 67-118%
ADP 2.5 uM 44-127%
Epinephrine 10 uM70-112%
Epinephrine 2.5 uM53-128%
Collagen 2.5 ug/mL75-114%
Collagen 1.25 ug/mL61-116%
Ristocetin 1.25 mg/mL78-17%
Ristocetin 0.50 mg/mL 0-7%
CPT code(s):
85576 x4
Note: The billing party has sole responsibility for CPT coding.  Any questions regarding coding should be directed to the payer being billed.  The CPT codes provided by GML are based on AMA guidelines and are for informational purposes only.
Test includes:
Platelet Aggregation of 4 agonists, two dilutions each: ADP, Epinephrine, Collagen and Ristocetin.
Spectrophotometry - Light Transmission
Platelet aggregation study
Clinical significance:
Platelet Aggregation testing is performed to confirm and identify if platelet dysfunction is due to an intrinsic platelet defect, congenital platelet defects, von Willebrand Disease, or exposure to platelet inhibiting agents.
Doctoral Director(s:)
Michelle Grant DO    
Review Date: 02/01/2023

Performing Locations

Geisinger Medical Center

Performing laboratory: Coagulation
Technical Lead: Margaret Knowles-Tuchman
Frequency: Daily, 8am-12 Noon
Performed STAT? No
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