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Test Code LMW Hep Low Molecular Weight Heparin Activity  

Clinical System Name

Low Molecular Weight Heparin Activity
 

Synonyms

anti-Xa activity
Heparin Activity, Low Molecular Weight
Heparin Low Molecular Weight
LMW Heparin
LMWH 

Description

 Low molecular weight heparins (LMWH) are used for the prevention and treatment of thromboembolic diseases. The quantitative determination of plasma LMWH levels is useful for monitoring treatment efficacy.

 

*Note: LMWH test is for Enoxaprin (Lovenox).

Sample Requirements

Specimen: Whole Blood

Container(s): Lt Blue/Citrate

Preferred Vol: 1.8 mL

Minimum Vol: N

 

Note:  Blood should be collected 4 hours after injection of LMW Heparin.    

 

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 this method is used it requires a 5 mL waste volume; 3 mL for size 2 French catheter or smaller. Blood must be trasferred to the  Lt Blue/Citrate tube by use of a  blood transfer device to ensure proper fill. 

Specimen should be centrifuged within 1 hour of collection.

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. Do not use blue band on tube label for correct fill volume, note fill line on tube. Test results are affected by incorrect blood volume. VAD is not the preferred method of collection for coag testing. If this method is used it requires a 5 mL waste volume; 3 mL for size 2 French catheter or smaller. Specimen should be centrifuged within 1 hour of blood draw. Double spin, freeze one aliquot of 1.0 mL plasma in plastic tube 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

Heparin activity is reported in Anti-Xa IU/mL (Anti-Xa International Units/mL). The therapeutic range for Low Molecular Weight Heparin will vary depending with the type and manufacturer. Questions about therapeutic ranges should be referred to the Pharmacy Department.
 

Methodology

Method: Chromogenic Substrate by STA® - Compact Analyzer

Analytical Volume: 1 mL plasma

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

Critical Values

Greater than or equal to 2.00 International Units/mL