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HelpTest Code LAB316 Low Molecular Weight Heparin Activity
Clinical System Name
Low Molecular Weight Heparin Activity
Synonyms
LAB316
LMW Hep
anti-Xa activity
Heparin Activity, Low Molecular Weight
Heparin Low Molecular Weight
LMW Heparin
LMWH
Sample Requirements
Specimen: Whole Blood
Container(s): Lt Blue/Citrate
Required Vol: one 1.8 mL tube or one 2.7 mL tube (do NOT over or under fill)
Minimum Vol: N
Note: Blood should be collected 4 hours after injection of LMW Heparin.
The required volume is enough for a PT, PTT, LMW Hep, and Fibrinogen on the same sample.
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 transferred 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
Main Campus CPA: Core Technologist will process specimen. Deliver blood directly to Core Coag bench.
Reject due to: Clotted, Hemolyzed, Insufficient quantity (underfill), or Improper collection (overfill).
Spin: Y
Aliquot: Y
Storage location: Core 14 Freezer ( -70 C).
Core Technologist: 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 the fill line on the 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 transferred to the Lt Blue/Citrate tube by use of the blood transfer device.
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 until solid one aliquot of 1.0 mL plasma in plastic tube at -70C (preferred) or -20C.
Non-Children's Hospital Off-site collection: Ship completely frozen on dry ice.
Children's Regional Clinics: Ship completely frozen in frozen Nalgene Labtop cooler with ice pack inside an insulated soft cooler.
Stability
| Specimen Type | Temperature | Time |
|---|---|---|
| Citrated platelet-poor plasma | Room temp | ≤4 h |
| 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: 206 987-2617 (Client Services)
CPT Codes
85520
Methodology
Method: Chromogenic Substrate by STA-R MAX
Analytical Volume: 1 mL plasma
This is enough for a PT, PTT, LMW Hep, 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.
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.
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: Low Molecular Weight Heparin Activity test is for Enoxaparin (Lovenox).
Critical Values
Greater than or equal to 2.00 International Units/mL