What is the ICD-10 (International Classification of Diseases, 10th Revision) code for an elevated International Normalized Ratio (INR)?

ICD-10 Code for Elevated INR

The ICD-10 code for an elevated International Normalized Ratio (INR) is R79.1 (Abnormal coagulation profile). This code is used to document elevated INR values when not attributed to anticoagulant therapy or other specific conditions.

Understanding INR and Its Clinical Significance

The International Normalized Ratio (INR) is a standardized measurement developed to address variability in prothrombin time (PT) results across different laboratories and thromboplastin reagents 1. While primarily designed for monitoring vitamin K antagonist therapy (like warfarin), INR values are often misused as general screening tests for coagulopathy 2.

Normal and Elevated INR Values:

• Normal INR range: 0.9-1.1 3
• INR above 1.5: Considered discoagulopathy with increased bleeding risk 3
• Therapeutic ranges for specific conditions:
  • Venous thromboembolism: 2.0-3.0 (target 2.5) 3
  • Mechanical heart valves: 2.5-3.5 (mitral) or 2.0-3.0 (aortic without risk factors) 3

Clinical Management of Elevated INR

Management depends on the degree of elevation and whether the patient is on anticoagulation therapy:

For Patients on Vitamin K Antagonists:

• INR ≥6.0 without bleeding: Consider oral vitamin K (1-2 mg); higher doses (5 mg) if INR >10 2
• Severe bleeding with elevated INR: Requires immediate reversal with intravenous prothrombin complex concentrate and oral vitamin K 2

For Patients Not on Anticoagulation:

• Mild elevations (INR <1.5): Generally require no intervention 2
• Elevated INR without obvious cause in elderly patients: Associated with higher mortality risk and may indicate underlying disease 4

Documentation and Coding Considerations

When documenting elevated INR:

1. Use R79.1 (Abnormal coagulation profile) for isolated elevated INR without known cause

2. If the elevated INR is due to anticoagulant therapy, code the appropriate:

   • Z79.01 (Long-term use of anticoagulants) plus
   • R79.1 (Abnormal coagulation profile) or
   • Specific code for anticoagulant adverse effect if applicable

3. If the elevated INR is secondary to another condition (like liver disease), code the underlying condition as primary

Coding Accuracy Considerations

ICD-10 codes for coagulation disorders have high sensitivity (100%) but lower specificity (79.3%) and positive predictive value (17.1%) 5. This means:

• These codes reliably rule out coagulation disorders when absent
• But may overidentify cases when present, requiring clinical verification

Important Caveats

• INR was specifically designed for monitoring vitamin K antagonist therapy and has limited validity in other clinical contexts 2
• Routine INR testing is not indicated for patients not on anticoagulation with no bleeding history 3
• In patients with elevated INR not on anticoagulation, investigate for underlying causes (liver disease, vitamin K deficiency, malnutrition) rather than treating the INR value itself

Remember that elevated INR without obvious cause in elderly patients may be a marker of poor prognosis and warrants careful clinical evaluation 4.