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Alias Names: RIPA / PLT AGG / Ristocetin Induced Platelet AGG
Methodology: Platelet Aggregation
Edit Date: 8/5/2010
Performed: Tuesday, Wednesday, Friday (by appointment)
Released: 24 hours
CPT Code: 85576 x6
Specimen Collection Details
Collection: Requires collection by appointment on Tuesdays, Wednesdays, or Fridays only before 11:00am at either the PeaceHealth Laboratories’ Patient Service Center, RiverBend Pavilion, 3377 RiverBend Drive (541.222.8203), or Northwest Specialty Clinics, 3355 RiverBend Drive, Suite 450 (541.222.7575). As testing is performed within one hour of collection, notify Special Coagulation with scheduled appointments or cancellations (541.743.4612).

Patient should fast 8 hours prior to collection and should not have taken aspirin within the previous 7 days. A list of drugs affecting platelet function and which should be avoided prior to this testing is listed at Platelet Active Drug List.

Collect SIX 4.5 mL light blue top tubes (sodium citrate). Fill tubes to the maximum draw, at least 90% full.

Handling: Label the specimens with tape (red tape if available) and write on tape: “DO NOT CENTRIFUGE.” Mix by gentle inversion 3-4 times. Do not over mix as this can cause platelet activation and clumping. Keep tube ambient. DO NOT CENTRIFUGE OR REFRIGERATE. DO NOT SEND SPECIMEN THROUGH A PNEUMATIC TUBE SYSTEM. Immediately transport as whole blood to the RiverBend Annex Central laboratory. Testing should be performed within one hour of collection. If possible, have the out-of-town patient wait while the main lab verifies specimen adequacy.
Standard Volume: 30 mL whole blood collected at one of the Patient Service Centers indicated above.
Minimum Volume: Varies with platelet count.
Transport: Ambient.
Comments: Test includes Ristocetin induced Platelet Aggregation (RIPA). Platelet aggregation evaluates platelet response to ADP, arachadonic acid, epinephrine, collagen, and ristocetin at two concentrations (RIPA test).

Platelet aggregation studies are useful in the evaluation of qualitative (functional) platelet abnormalities. This testing is indicated when a prolonged Platelet Function Analysis (PGA) result is obtained, and the platelet count is normal. Abnormal results are obtained in acquired conditions (uremia, drug exposure [especially aspirin], chirrhosis, etc.), and heredity conditions (von Willebrand disease, Glanzmann’s thrombasthenia, etc.).

Rejection Criteria: Clotted specimen or hemolysis.

Reference Range:
Pathologist interpretation accompanies report.

PeaceHealth Laboratories