Serotonin Releasing Assay (Sendout)

Test Information: The serotonin release assay is designed to detect heparin-dependent platelet antibodies in the serum from patients suspected of having Heparin-Induced Thrombocytopenia (HIT). Heparin-induced thrombocytopenia (HIT) associated with thrombosis is an immune complex mediated disorder that can cause morbidity and mortality in patients receiving heparin therapy. Prompt diagnosis is paramount to appropriate patient management.

• SRA is often useful for confirmation of weak or “inconclusive” results obtained with the highly sensitive PF4/ELISA.
• The SRA can also be used to evaluate samples for antibodies that cross-react with low molecular weight heparins such as Lovenox.

Ordering Restrictions: This test is only available following a positive or strong positive Heparin Induced Thrombocytopenia Reflexive Panel [HITRP] result.

Non-reflex orders require approval by the Laboratory Medicine Resident (LMR) on-call or Hematology Consult Group.

• Contact the resident via the paging operator at (206) 598-6190.
• Once approval is obtained, order in Epic using a LABUND (Laboratory Undefined) and include the name of the approver in the order comments.

The presence of “non-drug” antibodies reactive with platelets (e.g., HLA Class I, autoantibodies, platelet specific antibodies) in the patient’s serum can induce heparin independent release of serotonin in the SRA.

Testing with Lovenox® (enoxaparin) versus unfractionated heparin has not been validated as a useful guide to clinical management.

9 mL blood in RED TOP tube

Unacceptable: Any tube with anticoagulant

Outside Laboratories:

• Centrifuge sample and transfer serum to a separate plastic vial.
• Freeze serum at -20°C while awaiting shipment and transport on dry ice.
  • Samples may be refrigerated if received in lab <7 days after collection.

Stability: Refrigerated: 7 days; Frozen: Acceptable; Ambient: Unacceptable.

Centrifuge sample and transfer serum to a separate plastic vial. Refrigerate serum.

Processing Note: Refrigerated samples must reach Versiti Wisconsin within 7 days. If shipment is delayed, freeze sample at -20°C.

Sendouts:

• Complete a Versiti Wisconsin Platelet and Neutrophil Immunology Lab Requisition. Affix DLMP Billing and Results labels to the form.
• Order Versiti Test: 5508 (also known as Heparin-Dependent Antibody - SRA).
• Freeze serum at -20°C if the sample is nearing the 7-day stability limit. Transport on dry ice.
• Ship samples Monday through Friday via FedEx Priority Overnight.
  
  • If shipping on a Friday, select the "Saturday Delivery" option.

Stability: Refrigerated: 7 days; Frozen: Acceptable; Ambient: Unacceptable.