ICD-10-CM > R00-R99 > R70-R79 > R76 > R76.8 R76.8 Other specified abnormal immunological findings in serum Non-Billable/Non-Specific Codes R76.81Abnormal rheumatoid factor and anti-citrullinated protein antibody without rheumatoid arthritisR76.89Other specified abnormal immunological findings in serum