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Test Name:
Platelet Aggregation, Whole Blood
- SBMF No:
25044 - Performance Lab Name:
Hem-Coag - Test Mnemonic:
AGG PLT - ABN:
Not required - CPT Code:
85576 - LOINC Code:
21027-8 - Spec Type:
Whole blood - Spec Container:
Two (2) light blue top (3.2% buffered sodium citrate) tubes - Pref Vol:
10.0 mL - Min Vol:
5.0 mL - Fasting:
No - Patient Prep:
Schedule test with SBMF Hematology department
Obtain a "Platelet Aggregation History" sheet (form #910831) from SBMF (contains list of aspirin-containing products and requests previous coagulation tests results)
Patient’s platelet count must be greater than 100,000/cm³ in order to perform aggregation studies
Complete form and send it with specimen
Prior to test, patient should not receive aspirin or aspirin-containing medications for at least 1 week
Discontinue heparin therapy for at least 12 hours - Spec Collect:
Routine venipuncture
Avoid traumatic puncture - Spec Process:
Do not centrifuge
Do not remove plasma from cells
Do not expose sample to extreme tempratures - Spec Store Transport:
Room temperature – do not expose sample to extreme temperatures
Make arrangements for courier transport / do not use pneumatic tube transport
Sample must be tested within 1 hour of collection - Spec Stability:
1 hour room temperature (20-30°C) - Spec Reject:
Collection tubes not filled to full vacuum capacity
Sample not maintained room temperature
Sample contaminated with heparin
Sample contains clots
Sample received more than 1 hour after collection
Hemolyzed or lipemic sample - Methodology:
Luminescence Aggregometer - Use:
Used to detect well-characterized platelet dysfunctions and von Willebrand disease - Clinical Significance:
The test is intended to detect well characterized platelet dysfunctions and von Willebrand disease. These include effects in the membrane, storage granules, secretory mechanism, thromboxane synthesis and plasma co-factor deficiency. Detection of these abnormalities requires measurement of ATP secretion in response to thrombin, aggregation and ATP secretion in response to collagen, arachidonic acid and ristocetin. - Reference Range:
Interpreted by pathologist - Additional Test Info:
Interpretation: Von Willebrand disease is characterized by a deficiency of a plasma co-factor (vWF) required for platelet aggregation. The antibiotic ristocetin induces platelet aggregation in the presence of vWF and the GPI receptor. Thus, failure to aggregate in response to ristocetin is indicative of von Willebrand disease or absence of GPIB receptor (Bernard-Soulier Syndrome).
No aggregation in response to ristocetin is indicative of von Willebrand disease. In some cases, the prolonged lag time is the only indication of abnormality. Hyper-responsiveness to ristocetin may be seen in type IIB and platelet von Willebrand disease and can be confirmed by testing at a final concentration of 0.3 mg/mL ristocetin. Qualitatively abnormal and often bizarre curves with patterns of aggregation and disaggregation are often seen after aspirin, ibuprofen or similar drug ingestion. No aggregation in response to ristocetin may also be caused by lack of the GPI receptor in Bernard-Soulier Syndrome. Repeating ristocetin aggregation with the addition of normal plasma or concentrate vWF will correct the aggregation abnormality in von Willebrand disease but not in Bernard-Soulier Syndrome.
Thrombasthenias, abnormality of GPIIB – IIIA, is characterized by abnormal aggregation to collagen and ADP, with normal aggregation to ristocetin.
Interfering Drugs: Many drugs inhibit platelet function. Unless the aim of testing is to detect drug-induced inhibition, patients should be drug free prior to testing. The principle class of drugs inhibiting platelet aggregation and secretion are the non-steroidal anti-inflammatories. The clinician should be aware of any prescribed drugs. However, aspirin and ibuprofen are contained in many over the counter medicines. - Day Run:
Mon-Fri - Time Run:
Pre-schedule - Time Reported:
8 hours - Test Type:
COAGULATION
