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v1.0.0
ICD-10 Guide
DiagnosesRheumatoid Factor

Rheumatoid Factor

ICD-10 Coding for Rheumatoid Factor(M05.79, M06.9)

PRIMARY SPECIALTYRheumatology
COMPLEXITYHigh
LAST UPDATED09/15/2025
Sam Tuffun, PT, DPT
Physical Therapist | Medical Coding & Billing Contributor

Diagnosis Overview

What is Rheumatoid Factor?
Essential facts and insights about Rheumatoid Factor

Key Clinical Considerations:

  • Joint pain and swelling, particularly in the hands and feet
  • Positive rheumatoid factor test (RF) indicating autoimmune activity
  • Morning stiffness lasting more than 30 minutes

Clinical Information

Clinical Criteria & Documentation Requirements

  • Patient history of joint symptoms and duration
  • Results of rheumatoid factor test and other relevant serologies
  • Physical examination findings including joint tenderness and swelling

Coding Guidelines

Usage Guidelines & Examples

  • Usage guidelines: Use M05 codes for rheumatoid arthritis with RF; M06 for unspecified types.
  • Common errors: Misclassifying rheumatoid arthritis as osteoarthritis.

Code Exclusions

Important Exclusions

  • Osteoarthritis (M15)
  • Psoriatic arthritis (L40.5)

Related ICD-10 Codes

Primary Codes
M05.79
Rheumatoid arthritis with rheumatoid factor, unspecified site
M06.9
Rheumatoid arthritis, unspecified
Ancillary Codes
Z79.899
Differential Codes
M06.79
M05.9

Related CPT Codes

CPT codes will be available in a future update.

Specialty Focus

Primary Specialty

Rheumatology

Specialty Applications

  • Adults, particularly those aged 30-60 years
  • Rheumatology clinics, primary care settings

Coding Complexity

High Complexity

This diagnosis requires careful attention to:

  • Comprehensive clinical documentation
  • Accurate code selection based on clinical criteria
  • Proper exclusion considerations
  • Specialty-specific coding guidelines

Documentation

Documentation Templates

Billing Information

Billing Considerations

  • Ensure proper documentation for billing
  • Verify code specificity requirements
  • Check for any additional codes needed
  • Review payer-specific guidelines

Common Issues

  • Insufficient clinical documentation
  • Incorrect code selection
  • Missing supporting diagnoses
  • Timing and frequency documentation

Frequently Asked Questions

Documentation requirements?

Document patient history, physical exam findings, and lab results.

Billing considerations?

Ensure accurate coding based on the specific type of rheumatoid arthritis and associated symptoms.