American Association of Critical-Care Nurses (AACN) Certification Practice Test

What is the normal range for activated partial thromboplastin time (aPTT)?

1. 20-30 seconds

2. 25-35 seconds

3. 30-40 seconds

4. 15-25 seconds

The correct answer is: 25-35 seconds

The normal range for activated partial thromboplastin time (aPTT) is typically around 25 to 35 seconds. This test is crucial in evaluating the intrinsic and common pathways of coagulation, particularly in assessing coagulopathy or the efficacy of anticoagulation therapy. When interpreting aPTT results, it's important to recognize that various factors, including the specific testing methods and reagents used in different laboratories, can influence the reference range. However, the standard range of 25 to 35 seconds is widely accepted in clinical practice. Values falling outside this range may indicate a bleeding disorder or the need to adjust anticoagulant medications. This makes the identification of the correct normal range essential for healthcare professionals in critical care settings, ensuring appropriate patient management.