Differential Diagnosis for Elevated INR

The following differential diagnosis is organized into categories to help guide the thought process:

• Single Most Likely Diagnosis
  • Warfarin overdose or supratherapeutic dosing: This is the most likely diagnosis, as warfarin is a common anticoagulant that works by inhibiting vitamin K-dependent clotting factors, leading to an elevated INR.
• Other Likely Diagnoses
  • Vitamin K deficiency: A deficiency in vitamin K can lead to an elevated INR, as vitamin K is necessary for the production of clotting factors.
  • Liver disease: Liver disease, such as cirrhosis, can lead to an elevated INR due to decreased production of clotting factors.
  • Malnutrition: Malnutrition can lead to a deficiency in vitamin K, resulting in an elevated INR.
  • Antibiotic use: Certain antibiotics can interfere with vitamin K production, leading to an elevated INR.
• Do Not Miss Diagnoses
  • Sepsis: Sepsis can lead to disseminated intravascular coagulation (DIC), which can cause an elevated INR.
  • Malignancy: Certain types of cancer, such as pancreatic cancer, can lead to an elevated INR due to the production of tumor-related procoagulant factors.
  • Trauma: Severe trauma can lead to DIC, resulting in an elevated INR.
• Rare Diagnoses
  • Congenital coagulopathy: Certain congenital coagulopathies, such as factor VII deficiency, can lead to an elevated INR.
  • Amyloidosis: Amyloidosis can lead to an elevated INR due to the deposition of amyloid proteins in the liver, resulting in decreased production of clotting factors.
  • Inherited thrombophilias: Certain inherited thrombophilias, such as protein C or protein S deficiency, can lead to an elevated INR.

Each of these diagnoses has a brief justification, and the categories are organized to help prioritize the most likely and critical diagnoses.