ICD-10 Code M05.842 – Other rheumatoid arthritis with rheumatoid factor of left hand (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code M05.842 – Other rheumatoid arthritis with rheumatoid factor of left hand
What it is
This code identifies rheumatoid arthritis affecting the left hand, with rheumatoid factor present, but not a more specific rheumatoid arthritis subtype. Use it when the provider documents RA in the left hand and links it to rheumatoid factor.
Clinical signs
Typical findings include inflammatory joint pain, swelling, stiffness, and reduced hand function. Clinical features vary; refer to documentation for laterality, joint involvement, and evidence of rheumatoid factor.
When to use this code
Use this code when the record clearly states other rheumatoid arthritis with rheumatoid factor involving the left hand. It fits visits for established RA in the left hand, whether the note describes active disease, chronic disease, or follow-up care. Check documentation if the hand is not specified or if another RA category is documented.
Do not use for
Do not use it for rheumatoid arthritis without rheumatoid factor, or when the right hand, both hands, or another joint is documented instead. Check documentation if the provider uses a different RA subtype.
Coding tip
Verify both the rheumatoid factor association and left-hand laterality before assigning M05.842.