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HelpTest Code LAB316 Low Molecular Weight Heparin Activity
Clinical System Name
Low Molecular Weight Heparin Activity
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).
Sample Requirements
Container(s): Lt Blue/Citrate
Required Vol: (1) 1.8 mL or (1) 2.7 mL
Minimum Vol: N
Note: This is enough for a PT, PTT, TT, Fibrinogen, and LMWH to be run on the same sample.
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. Please review the Coagulation Lab Collection Job Aid for detailed instructions.
Processing Instructions: Main Campus
Deliver whole blood to Coag bench. Coag Technologist will process.
Reject due to: clotted, insufficient quantity (underfill), or improper collection (overfill).
Spin: Y
Aliquot: Y
Storage location: Core 14 Freezer ( -70 C).
Specimen should be centrifuged within one hour of collection. Transfer upper 3/4 layer of plasma to plastic tube affixed with large Epic aliquot label. Do not pool. Assay immediately.
Processing Instructions: Offsite & Regional Clinics
Reject due to: clotted, insufficient quantity (underfill), or improper collection (overfill).
Spin: Y
Aliquot: Y
Storage location: -70 C (preferred) or -20 C.
Specimen should be centrifuged within one hour of collection. Double spin, transfer upper 3/4 layer of plasma to plastic tube affixed with large sample label. Freeze one aliquot of plasma at -70 C (preferred) or -20 C. Preferred plasma volume: 1.0 mL, minimum plasma volume: 0.6 mL. Do not pool.
Non-Children's Hospital Offsite collection: Ship completely frozen on dry ice.
Children's Hospital Regional Clinic collection: 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 |
Performing Laboratory
Seattle Children's Laboratory
Department
Department: Coagulation
Phone Number: 206 987-2617 (Client Services)
Synonyms
LAB316
LMW Hep
anti-Xa activity
Heparin Activity, Low Molecular Weight
Heparin Low Molecular Weight
LMW Heparin
LMWH
Availability
| STAT | Performed | TAT |
|---|---|---|
| Y |
Daily |
1 h |
Methodology
Method: Chromogenic substrate assay by STA-R MAX
Analytical Volume: 100 uL plasma
Limitations: Method is affected by moderate lipemia, moderate hemolysis, moderate icterus, insufficient quantity (underfill), improper collection (overfill), improper processing, and improper storage. 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.
CPT Codes
85520
Critical Values
Greater than or equal to 2.00 International Units/mL