Understanding PT and INR in Nursing

Sep 17, 2024

Unit 3: Laboratory Values and Nursing Management

Key Topics

  • Prothrombin Time (PT)
  • International Normalized Ratio (INR)
  • Partial Thromboplastin Time (PTT)

Prothrombin Time (PT)

  • Definition: Amount of time for blood to clot in relation to prothrombin.
  • Normal Range: 11 to 12.5 seconds.
  • Coagulation Cascade: Complex process; understanding aids in grasping differences in clotting times and drug impacts.

International Normalized Ratio (INR)

  • Definition: Ratio of patient’s PT to an internationally agreed PT standard.
  • Normal INR: Approximately 1 (range 0.8 to 1.1).
  • Therapeutic INR: Higher than normal, used for conditions with high clot risk.
    • Baseline: 1.5 to 2.
    • DVT Prophylaxis, Atrial Fibrillation, Orthopedic Surgery: 2 to 3.
    • Prosthetic Heart Valve: 3 to 4 (high risk of clotting).

Causes of Altered PT/INR

  • High PT/INR:
    • Liver disease (impaired clotting factor production).
    • Hereditary factors (e.g., hemophilia).
    • Vitamin K deficiency (needed for clotting factor production).
    • Coumadin (Warfarin) therapy (blocks Vitamin K action).
  • Low PT/INR:
    • Excessive Vitamin K intake or replacement.

Patient Management

  • High PT/INR:
    • Vitamin K administration or dietary adjustments.
    • Fresh Frozen Plasma (FFP) for immediate clotting factor replacement.
    • Bleeding precautions (gentle toothbrushing, use of clippers instead of razors).
    • Education on consistent Vitamin K intake.
  • Low PT/INR:
    • Anticoagulation therapy (e.g., Coumadin, Heparin).
    • Thrombolytics for life-threatening clots (e.g., TPA).

Signs and Symptoms

  • Elevated PT/INR: Increased bleeding, bruising, mental status changes, excessive surgical bleeding.
  • Low PT/INR: Risk of thrombus (clot formation) or embolus (traveling clot).

Important Notes

  • Vitamin K vs. Potassium: Vitamin K affects clotting, not to be confused with potassium (k+), an electrolyte.
  • Thrombus vs. Embolus: Thrombus is stationary, embolus moves and can cause blockages in lungs (PE), heart (MI), or brain (stroke).

Additional Context

  • Atrial Fibrillation: Heart condition increasing clot risk due to atria not pumping properly.
  • Orthopedic Surgery: Increased clot risk due to immobility and trauma, requiring INR management.
  • Prosthetic Valves: High thrombotic risk, needs careful INR monitoring.

These notes cover the essential topics discussed in the lecture on laboratory values, emphasizing the importance of understanding PT and INR in clinical settings, including the causes, implications, and management of their alterations.