M05.A

Billable code

Abnormal rheumatoid factor and anti-citrullinated protein antibody with rheumatoid arthritis

The ICD-10 code for abnormal rheumatoid factor and anti-citrullinated protein antibody with rheumatoid arthritis is M05.A.

Clinical notes

Code first

This code represents a manifestation of an underlying disease. Coding convention requires the underlying (etiology) code to be sequenced first, with this code listed second.

rheumatoid arthritis with rheumatoid factor by site, if known (M05.00 to M05.8A)

Documentation support

General coding-documentation guidance — not a substitute for payer-specific requirements or professional coding judgment.

•This code represents a manifestation. Documentation should identify the underlying condition, which must be coded first.
•As a general rule, code to the highest level of specificity supported by the documentation in the medical record.

Related codes in this category

Associated MS-DRGs

M05.A can serve as the principal diagnosis for these Medicare Severity Diagnosis-Related Groups.

Informational only — actual DRG assignment also depends on procedures, complications/comorbidities (CC/MCC), discharge status, and payer-specific rules not reflected here.