Coagulation Studies or Coagulation Panel
The collective term for PT, PTT, and INR laboratory tests when presenting a patient is "coagulation studies" or "coagulation panel" (also called "coag panel" or "coags" in clinical shorthand).
Standard Terminology in Clinical Practice
When presenting patients, these tests are most commonly referred to as:
- "Coagulation studies" - the most formal and widely accepted term
- "Coag panel" - common shorthand in clinical settings
- "Coags" - informal bedside terminology
The individual components are:
- PT (Prothrombin Time) - measures the extrinsic and common coagulation pathways, reported in seconds 1, 2
- INR (International Normalized Ratio) - a standardized mathematical conversion of PT using the formula INR = (PT/MNPT)^ISI, primarily designed for monitoring vitamin K antagonist therapy 1, 3
- PTT or aPTT (Activated Partial Thromboplastin Time) - measures the intrinsic and common coagulation pathways, reported in seconds or as a ratio 4
Important Clinical Context
The INR was specifically developed for monitoring warfarin therapy and is technically invalid in other clinical settings 2. Despite this limitation, INR has been widely adopted as a universal reporting system, which can lead to misinterpretation 2. When presenting patients not on vitamin K antagonists, PT should ideally be reported in seconds or as a PT ratio rather than INR 2.
The term "coagulation studies" encompasses the functional assessment of the clotting cascade and is distinct from other hemostasis tests like platelet count or fibrinogen levels, though these may be ordered together in comprehensive bleeding or thrombosis workups 5.