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Lab Manual for Moffitt-Long and Mount Zion

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Heparin-PF4 Complex Antibodies (Revised Test)

Item Value
Approval req'd? No
Available Stat? No
Utilization Guidelines The pretest likelihood of HIT can be assessed by the 4T's:

Category 2 points 1 point 0 points
Degree of thrombocytopenia Fall > 50% and nadir ≥ 20K fall 30-50% or nadir 10K-19K Fall < 30% or nadir < 10
Timing of fall 5-10 days post heparin or ≤ 1 day if prior exposure < 30 days Possibly within 5-10 days, post 10 days or ≤ 1 day if heparin exposure 30-100 days prior ≤ 4days without recent exposure
Thrombsis or sequelae New thrombosis; skin necrosis; acute systemic reaction post IV unfract. heparin Progressive or recurrent thrombosis; skin erythema w/out necrosis; suspected thrombosis only None
Other cause of thrombocytopenia None apparent Possible Definite


Score Probability of HIT
1-3 Low
4-5 Intermediate
6-8 High


Adapted from: Cuker A, Ortel TL. ASH evidence-based guidelines: is the IgG-specific anti-PF4/heparin ELISA superior to the polyspecific ELISA in the laboratory diagnosis of HIT? Hematology Am Soc Hematol Educ Program. 2009:250-2.
Test code HIPAB
Test group HIT
Performed by Quest
Sendout? Yes
Method Enzyme Linked Immunosorbent Immunoassay
Collection Instructions 1. Check the expiration date on the label of the blue top vacutainer before drawing the patient.

2. For blood collection in a sodium citrate blue top, the tube must be filled to above the Minimum Fill Indicator on the tube. It is crucial to wait and allow the tube to stop filling before removing it from the needle.

3. With use of a butterfly needle, draw about 1 cc using a separate blue top to remove air from tubing, discard the first tube and then draw a second blue top tube filled to the full extent of the vacuum.

4. Tubes should not be filled past the Maximum Fill dashed line by either using a syringe or removing the tube cap.
Container type Blue top filled to full extent of vacuum
Amount to Collect 2.7 mL blood
Sample type Citrated plasma
Preferred volume 1 mL plasma
Min. Volume 0.5 mL plasma
UCSF Rejection Criteria Samples collected in outdated blue top vacutainer. Over-filled or under-filled tubes may be rejected.
Processing notes Deliver specimen immediately to Hematology M524 for processing.

Separate and freeze ≥ 1.5 mL of plasma at -20C in a plastic tube within 1 hour of collection.
Ref Lab Rejection Criteria Thawed sample received
Normal range Heparin-Induced PLT AB: Negative
Patient O.D.: <0.400
Synonyms HIT; heparin induced thrombocytopenia; platelet factor 4; HIT panel; platelet factor 4; HPA; heparin induced platelet antibody
Turn around times 3-5 days. Test set up Sunday – Thursday.
Additional information A negative test does not exclude thrombotic risk due to heparin induced thrombocytopenia (HIT), nor does a positive test exclude other causes of thrombocytopenia. Correlation with Serotonin Release Assay (SRA), platelet counts, and clinical findings can be important for diagnosis of HIT.

Antibodies to heparin-PF4 complexes are found in the majority of patients with clinical findings of heparin-induced thrombocytopenia (HIT), but also in variable numbers of heparinized patients without thrombocytopenia.

The pretest likelihood of HIT can be assessed by the 4T's:

Category 2 points 1 point 0 points
Degree of thrombocytopenia Fall > 50% and nadir ≥ 20K fall 30-50% or nadir 10K-19K Fall < 30% or nadir < 10
Timing of fall 5-10 days post heparin or ≤ 1 day if prior exposure < 30 days Possibly within 5-10 days, post 10 days or ≤ 1 day if heparin exposure 30-100 days prior ≤ 4days without recent exposure
Thrombsis or sequelae New thrombosis; skin necrosis; acute systemic reaction post IV unfract. heparin Progressive or recurrent thrombosis; skin erythema w/out necrosis; suspected thrombosis only None
Other cause of thrombocytopenia None apparent Possible Definite


Score Probability of HIT
1-3 Low
4-5 Intermediate
6-8 High


Adapted from: Cuker A, Ortel TL. ASH evidence-based guidelines: is the IgG-specific anti-PF4/heparin ELISA superior to the polyspecific ELISA in the laboratory diagnosis of HIT? Hematology Am Soc Hematol Educ Program. 2009:250-2.
CPT coding 86022-90
Last Updated 3/19/2013 1:50:51 PM
Entry Number 1457

If you have additional questions regarding this test, please call: 415-353-1667

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