R76.81Abnormal rheumatoid factor and anti-citrullinated protein antibody without rheumatoid arthritis

R76.81 is the ICD-10-CM diagnosis code for abnormal rheumatoid factor and anti-citrullinated protein antibody without rheumatoid arthritis. It belongs to category R76 (other abnormal immunological findings in serum), block R70-R79 (abnormal findings on examination of blood, without diagnosis) and chapter 18 (symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified). It is billable, so it can be reported on its own for dates of service from October 1, 2026 through September 30, 2027.

Within R76.8, choose R76.81 (Abnormal rheumatoid factor and anti-citrullinated protein antibody without rheumatoid arthritis) only when documentation doesn't support a more specific option: other specified abnormal immunological findings in serum (R76.89).

Don't report R76.81 together with the conditions in its Excludes1 note: rheumatoid arthritis with rheumatoid factor (M05.-).

It is not a CC or MCC, so as a secondary diagnosis it doesn't change the MS-DRG severity level.

In MS-DRG v44.0, it is part of the grouping logic for DRG 814 (Reticuloendothelial and Immunity Disorders with MCC, relative weight 2.0729), DRG 815 (Reticuloendothelial and Immunity Disorders with CC, relative weight 1.0444) and DRG 816 (Reticuloendothelial and Immunity Disorders without CC/MCC, relative weight 0.7381), in MDC 16 (Diseases and Disorders of the Blood and Blood Forming Organs and Immunological Disorders), as a principal or secondary diagnosis. The DRG a claim lands in depends on the principal diagnosis, procedures and any CC/MCC secondary diagnoses.

It was added in FY2026, effective October 1, 2025.