Laboratory Test Guide

Serotonin Releasing Assay (Sendout)

General Information

Lab Name

Serotonin Release Assay (SRA) (Sendout)

Lab Code

RSRAG

Epic Name

Serotonin Release Assay (SRA) (Sendout)

External Test Id

5508

Description

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.

References

Versiti Wisconsin Heparin-Induced Thrombocytopenia (SRA) Description

Synonyms

5508, Heparin-Induced Thrombocytopenia Confirmatory Testing, HIT Confirmation, SRA, SRA UFH, SRA unfractionated heparin

Components

Code	Name
RSRLD	Serotonin Release Assay Low Dose Result
RSRHD	Serotonin Release Assay High Dose Result
RSRAR	Serotonin Release Assay Result
RSRINT	Serotonin Release Assay Interpretation

Interpretation

Method

14C-Serotonin release assay (SRA)

Reference Range

See individual components

Interferences and Limitations

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.

Ordering & Collection

Specimen Type

Blood

Collection

9 mL blood in RED TOP tube

Unacceptable: Any tube with anticoagulant

Forms & Requisitions

Versiti Wisconsin Platelet & Neutrophil Immunology Lab Requisition

Approval Required

Non-reflex orders require approval by the Laboratory Medicine Resident or Hematology Consult Group.

Handling Instructions

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.

Quantity

requested: 5 mL serum
minimum: 1 mL serum

Processing

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.