UCSF Departments of Pathology and Laboratory Medicine | Lab Manual | Laboratory Test Database | Heparin-PF4 Complex Antibodies (Revised Test)

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Heparin-PF4 Complex Antibodies (Revised Test)

Item

Value

Approval req'd?

Available Stat?

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Samples collected in outdated blue top vacutainer.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

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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Heparin-PF4 Complex Antibodies (Revised Test)