Abstract:  

This study was conducted to evaluate current unfractionated heparin (UFH) dosing regimen and establish an institutional therapeutic range for UFH in a public hospital in Jordan. In the first part, medical records of 241 patients who received UFH were reviewed retrospectively. In the second part, blood samples were withdrawn from 60 patients on UFH, and activated partial thromboplastin time and anti-Xa assay were measured. Most activated partial thromboplastin time readings were not therapeutic (91.4%) and recurrence of thrombosis was reported in 35.3% of patients. In the second part, therapeutic activated partial thromboplastin time range corresponding to the UFH concentration of 0.3 to 0.7 anti-factor Xa unit/mL was 56 to 95 seconds, which corresponds to an activated partial thromboplastin time range of 1.5 of 2.8 times the mean control value. The traditional activated partial thromboplastin time range ratio of 1.5 to 2.5 times the control value can result in subtherapeutic UFH levels.