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Updated: Mar 16, 2026

Rapid Point-of-Care Assay of Enoxaparin Anticoagulant Efficacy in Whole Blood
Published on: October 12, 2012
Effect of Subcutaneous Unfractionated Heparin Prophylaxis on Activated Partial Thromboplastin Time: A Retrospective
Molly H Thompson1, Sylvia H Wilson2, Brittany L Toussaint1
1Department of Pharmacy Services, Medical University of South Carolina, 150 Ashley Avenue, MSC 584, Charleston, SC, 29425, USA.
Study Objective:
Characterize the incidence of elevated aPTT results in patients treated with prophylactic, subcutaneous unfractionated heparin (UFH).
Design:
Retrospective, cohort analysis.
Setting:
Single-center, university hospital.
Measurements:
Evaluation of 257 patients with activated partial thromboplastin time (aPTT) testing both prior to and following subcutaneous (SC) unfractionated heparin (UFH) therapy.
Main Results:
Evaluated patients received UFH 5000 units every 8 hours. Baseline aPTT values were within the normal range (mean±SD, 32.0±8.5 seconds). After initiation of UFH, aPTT values increased (mean±SD, 37.6±15.2 seconds). After 24 hours of SC UFH, mean aPTT values (mean±SD, 38.6±15.5) exceeded the normal laboratory range (23.3-35.7 seconds). An elevated aPTT result after UFH was associated with baseline aPTT, length of therapy, and weight-based UFH dose. A significant association was not identified between aPTT elevation and age, race, sex, history of liver disease, type of admission, or transfusion of blood products.
Conclusions:
Treatment with UFH resulted in a small, but significant, increase in aPTT.
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