2026 ICD-10-CM Diagnosis Code M05.A
Abnormal rheumatoid factor and anti-citrullinated protein antibody with rheumatoid arthritis
- ICD-10-CM Code:
- M05.A
- ICD-10 Code for:
- Abn rheu fctr & anti-citrul protein antibody w rheu arthrit
- Is Billable?
- Yes - Valid for Submission
- Code Navigator:
M05.A is a billable diagnosis code used to specify a medical diagnosis of abnormal rheumatoid factor and anti-citrullinated protein antibody with rheumatoid arthritis. The code is valid during the current fiscal year for the submission of HIPAA-covered transactions from October 01, 2025 through September 30, 2026.
New 2026 ICD-10-CM Code
M05.A is new to ICD-10-CM code set for the FY 2026, effective October 1, 2025. The National Center for Health Statistics (NCHS) has published an update to the ICD-10-CM diagnosis codes which became effective October 1, 2025. This is a new and revised code for the FY 2026 (October 1, 2025 - September 30, 2026).
Tabular List of Diseases and Injuries
The following annotation back-references are applicable to this diagnosis code. The Tabular List of Diseases and Injuries is a list of ICD-10-CM codes, organized "head to toe" into chapters and sections with coding notes and guidance for inclusions, exclusions, descriptions and more.
Code First
Code FirstCertain conditions have both an underlying etiology and multiple body system manifestations due to the underlying etiology. For such conditions, the ICD-10-CM has a coding convention that requires the underlying condition be sequenced first followed by the manifestation. Wherever such a combination exists, there is a "use additional code" note at the etiology code, and a "code first" note at the manifestation code. These instructional notes indicate the proper sequencing order of the codes, etiology followed by manifestation.
Index to Diseases and Injuries References
The following annotation back-references for this diagnosis code are found in the injuries and diseases index. The Index to Diseases and Injuries is an alphabetical listing of medical terms, with each term mapped to one or more ICD-10-CM code(s).
- Abnormal, abnormality, abnormalities - See Also: Anomaly;
Index of External Cause of Injuries
References found for this diagnosis code in the External Cause of Injuries Index:
- Abnormal, abnormality, abnormalities
- rheumatoid factor and anti-citrullinated protein antibody
- with rheumatoid arthritis
Replacement Code
M05A replaces the following previously assigned ICD-10-CM code(s):
- M05.9 - Rheumatoid arthritis with rheumatoid factor, unspecified
Code History
- FY 2026 - Code Added, effective from 10/1/2025 through 9/30/2026
