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Heparin Level (Unfractionated heparin)
|Performed by||Parnassus & Mission Bay Hematology|
|In House Availability||Monday - Friday
Note: If testing is medically necessary on evenings or weekends, order STAT
|Method||Chromogenic Synthetic Substrate|
|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.
Indicate exact brand and type of heparin or heparinoid being used on requisition.
For patients with Hct's ≥ 55% please contact Hematology (Parnassus 3-1747 or Mission Bay ) to obtain blue top tubes with adjusted citrate volumes in order to maintain the proper citrate to plasma ratio for coagulation studies.
|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|UCSF Rejection Criteria||Samples collected in outdated blue top vacutainer.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 to Hematology lab ASAP for processing.
Separate plasma at 5000 rpm for 8 min. Make two separate 1 mL aliquots in plastic tubes and freeze at -20C
|Normal range|| Therapeutic:
|Critical value||> 0.70 anti-Xa U/mL|
|Synonyms||Monitoring Anticoagulation; UFH; Unfractionated heparin; Anti Factor 10a; Anti factor Xa|
|Turn around times||1-3 days|
|Additional information||The utility of measuring heparin levels has been demonstrated in a few clinical settings. Patients receiving unfractionated heparin require heparin levels if there is heparin resistance (adults requiring more than 35,000 units/day) or if a lupus anticoagulant is present; in such conditions the PTT may not be an accurate indicator of anticoagulation.
The Stachrom Heparin assay uses exogenous activated factor Xa and exogenous antithrombin. This combination can overestimate the in vivo therapeutic effect of heparin and low-molecular weight heparin in the setting of severe antithrombin deficiency.
In addition to congenital antithrombin deficiency, the possibility of antithrombin deficiency should be considered in the setting of prematurity, nephrotic syndrome, cirrhosis, L-asparaginase therapy, disseminated intravascular coagulation, microangiopathic hemolytic anemia, venoocclusive disease, or other severe debilitating illness. In these clinical settings, consideration could be made for ordering an antithrombin level to confirm accurate monitoring of anticoagulant effect by the anti-Xa assay.
The appropriate therapeutic range will vary with the disease and the treatment intensity desired. An overview of recommendations is available in the laboratory manual for reference purposes only in the entry: Heparin Laboratory/Dosing Algorithm. Recommendations for therapy and monitoring are also available through the Hematology consultation services: for adults, pager 443-4276, for pediatrics pager 443-6966.
|LDT or Mod FDA?||Yes|
|Last Updated||11/19/2015 3:47:56 PM|