Establishing a therapeutic range for heparin therapy
P Brill-Edwards, JS Ginsberg, M Johnston… - Annals of internal …, 1993 - acpjournals.org
P Brill-Edwards, JS Ginsberg, M Johnston, J Hirsh
Annals of internal medicine, 1993•acpjournals.orgObjective: To compare two methods of determining a therapeutic range of activated partial
thromboplastin time (aPT) results. Design: Cohort studies. Setting: Referral teaching
hospital. Patients: Inpatients who received unfractionated heparin intravenously for venous
thromboembolic disease. Measurements: A therapeutic range determined by aPT ratios of
1.5 to 2.5 times the control value as compared with a therapeutic range determined by
protamine titration heparin levels of 0.2 to 0.4 U/mL. Results: For all aPT reagents studied, a …
thromboplastin time (aPT) results. Design: Cohort studies. Setting: Referral teaching
hospital. Patients: Inpatients who received unfractionated heparin intravenously for venous
thromboembolic disease. Measurements: A therapeutic range determined by aPT ratios of
1.5 to 2.5 times the control value as compared with a therapeutic range determined by
protamine titration heparin levels of 0.2 to 0.4 U/mL. Results: For all aPT reagents studied, a …
Objective
To compare two methods of determining a therapeutic range of activated partial thromboplastin time (aPT) results.
Design
Cohort studies.
Setting
Referral teaching hospital.
Patients
Inpatients who received unfractionated heparin intravenously for venous thromboembolic disease.
Measurements
A therapeutic range determined by aPT ratios of 1.5 to 2.5 times the control value as compared with a therapeutic range determined by protamine titration heparin levels of 0.2 to 0.4 U/mL.
Results
For all aPT reagents studied, a ratio of 1.5 times the control value is much less than a minimum protamine titration heparin level of 0.2 U/mL. Various manufacturers' aPT reagents and reagent lots from the same manufacturer show considerable variation in response to heparin and therefore have different therapeutic ranges.
Conclusions
A different dose of heparin would be required to produce an aPT ratio of 1.5 times the control value, depending on the reagent used. Establishing a therapeutic range for aPT results using protamine titration heparin levels of 0.2 to 0.4 U/mL as a reference standard is practical and compensates for the variable response of aPT reagents to heparin.
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