Abstract
The relation between hourly heparin sodium requirements and the presence or absence of thromboembolic disease (TED) was investigated. Patients (12) with verified TED required 1696 .+-. 394 units/h (mean .+-. SD) and 9 patients without disease required 1033 .+-. 343 units/h of continuous heparin sodium to attain a target-activated partial thromboplastin time. The requirements in relation to body weight were 25 .+-. 4 units/kg per h for the 12 with verified TED and 15 .+-. 3 units/kg per h for the 9 without disease. Apparently heparin requirements are related to the presence or absence of TED and are diagnostically important; large requirements coincide with active TED and lesser requirements suggest absence of a thromboembolic process.