Platelet Antibody Screen for Platelet Transfusion Refractory Patients
Label Mnemonic: PLTAB
Epic code: LAB4388
Downtime form: A-1a Doctor-Provider Orders - Pathology Blood Center
DeGowin Blood Center - Blood Bank
C271 GH
Collection Medium:
Pink top tube 6 mL (K2-EDTA) Lavender top tube 3 mL (EDTA)
Adult minimum: 5 mL
Pediatric minimum: 2 mL
Rejection Criteria:
Specimen must be labeled with patient's first and last name and medical record number. Specimens will be rejected if information is not on the label when received.
Delivery Instructions:
Deliver to laboratory immediately after collection.
Testing Schedule:
0700-1400 Monday through Friday. All tests must be approved by the Clinical Pathology Resident (Pager 3404). The sample should be delivered by 10:00 a.m. for same-day testing. Result is accompanied by professional consultation and if indicated a platelet crossmatch with platelets in inventory will be performed to identify platelets for transfusion.
Reference Range:
No reactivity.
This test is for patients known to be refractory to platelet transfusions. All tests must be approved by the Clinical Pathology Resident (Pager 3404) and we highly recommend you order a "Consult DeGowin Blood Center Physician" (Lab7611) so DeGowin Faculty can assist with the assessment and management of these patients.

This testing is used by the Blood Bank to determine whether platelet refractoriness may be immune-mediated. This is a screening test using the Immucor Capture-P assay to detect IgG antibodies against HLA or platelet antigens. Negative results indicate no detection of allo- or auto-antibodies to platelets. Positive results indicate detection of anti-platelet allo- and/or auto-antibodies. If variable reactivity is demonstrated with this test a platelet crossmatch is generally performed. In some cases, identification of HLA specific antibodies may assist in the identification of platelets for transfusions. This testing requires a separate order and is done by an outside reference laboratory. It generally takes take 3-5 days to receive HLA matched platelets. This test is not recommended for the diagnosis of idiopathic thrombocytopenic purpura (ITP) due to low sensitivity and specificity (Blood 1997 V89, Pg 1112).
Test Limitations:
Many patients are refractory to platelet transfusion for non-immune causes such as DIC, bleeding, splenomegaly regardless of the results of this test. No one test is capable of detecting all antibodies to platelets. Our experience indicates that this test can be utilized to detect compatible platelets (CCI>5) in about 1/3 of platelet transfusion-refractory patients.
Capture-P solid phase assay from Immucor. Platelet antigens are captured on a well and incubated with patient serum. Antibody binding is detected using IgG coated indicator RBCs.
CPT Code:
See Additional Information:
Specimens Requiring Immediate Delivery