A standardized procedure for specimen collection is essential to achieve accurate and reliable coagulation measurements (1). Efforts have been made to identify the most suitable procedures for collecting, handling, and storing specimens for coagulation testing (2)(3)(4)(5)(6), including a recommendation that samples be centrifuged at room temperature (7). There is no definitive evidence, however, that centrifugation at alternative temperatures might significantly influence results of coagulation testing. A single practiced phlebotomist collected blood from 12 healthy volunteers and 13 consecutive patients on oral anticoagulant therapy directly into three 4.5-mL siliconized evacuated tubes containing 0.5 mL of 0.105 mol/L buffered trisodium citrate (Becton Dickinson), using a 20-gauge, 0.80 × 19 mm Venoject® multisample straight needle (Terumo Europe NV). Venipunctures were performed in the morning of the same day …