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Test Code HEP UNF Unfractionated Heparin Activity  

Clinical System Name

Unfractionated Heparin Activity
 

Synonyms

anti-Xa activity
HEP UNF
Heparin Activity Unfractionated
Heparin Unfractionated
UFH

Description

Unfractionated heparin (UFH) is used for the prevention and treatment of thromboembolic diseases. The quantitative determination of plasma unfractionated heparin levels is useful for monitoring treatment efficacy.

Sample Requirements

Specimen: Whole Blood

Container(s): Lt Blue/Citrate

Preferred Vol: 1.8 mL

Minimum Vol: N

 

Note:  Preferred method of collection is venipuncture with vacuum fill.  Test results are affected by incorrect blood volume.  Use of a Vascular Access Device for the  collection of coag testing is not recommended.

 

If a venipuncture is not possible and drawing from a line is necessary:

a. Draw from a heparin-free line.

b. If patient has a line infused or flushed with heparin, such as an arterial line or central venous line, waste the following volume:

   A 6-mL waste volume for PIVs, PICCs, temporary venous lines (femoral, jugular) and Baby Broviacs.

  A 12-mL waste volume for all other permanent lines (Hickman, Portacath, HD, tunneled lines).

Processing Instructions

Reject due to: Clotted, Hemolyzed, Insufficient quantity, and  Improper collection.

Spin:N

Aliquot:N

Temp:RT

Storage location: Core 6 Freezer  ( -70 C).

 

Note: Deliver blood to Core Coag bench.  Coag Technologist will process. Specimen should be centrifuged within 1 hour of collection. Spin whole blood, remove plasma. Transfer upper 3/4 layer of plasma to plastic tube affixed with large computer label.

 

 

 

Off-site collection: Preferred method of collection is venipuncture with vacuum fill. Test results are affected by incorrect blood volume, note fill line on tube.  Use of a Vascular Access Device for the collection of coag testing is not recommended.

 

If a venipuncture is not possible and drawing from a line is necessary:

a. Draw from a heparin-free line.

b. If patient has a line infused or flushed with heparin, such as an arterial line or central venous line, waste the following volume:

   A 6-mL waste volume for PIVs, PICCs, temporary venous lines (femoral, jugular) and Baby Broviacs.

  A 12-mL waste volume for all other permanent lines (Hickman, Portacath, HD, tunneled lines).

 

Specimen should be centrifuged within 1 hour of collection. Double spin, transfer upper 3/4 layer of plasma to plastic tube affixed with large computer label. Freeze 2 aliquots of 1.0 mL plasma in plastic tubes at -70C.

Ship frozen on dry ice.

Stability

Specimen Type Temperature Time
Citrated platelet-poor plasma Room temp N
  Refrigerated N
  Frozen   -20 C or -70 C 3 m

 

Availability

STAT Performed TAT
Y

Daily

1 h

 

Performing Laboratory

Seattle Children's Laboratory    

 

Department

Department:  Coagulation

Phone Number: 206 987-2578

 

 

 

Reference Range

This assay requires antithrombin III (ATIII) in patient's plasma. Low level of ATIII may underestimate the heparin level.

Methodology

Method: Chromogenic Substrate by STA® - Compact Analyzer

Analytical Volume: 1 mL

This is enough for a PT, PTT, TT, and Fibrinogen on the same sample.

 

Limitations: Results affected by moderate lipemia, moderate hemolysis, and moderate icterus.

High hematocrit greater than or equal to 56% requires a citrate adjusted tube.

CPT Codes

85520

Special Instructions

Links to:

Consent Forms

Algorithms

Critical Values

Greater than or equal to 1.10 International Units/mL

 

Heparin activity is reported in Anti-Xa IU/mL (Anti-Xa International Units/mL). The therapeutic range for Unfractionated Heparin Activity is 0.3 - 0.6 Anti-Xa IU/mL.