Anti-cyclic citrullinated peptide antibody is usually detected by ELISA, the normal range is not the same in different laboratories, and must be combined with the reference range of different laboratories to determine. 1. Anti-cyclic citrullinated peptide antibody is a rheumatoid arthritis specific antibody, according to the values provided by different laboratories, if it is higher than the normal range, it should be combined with the clinical symptoms to consider whether there is rheumatoid arthritis. 2. In the absence of any clinical symptoms, only anti-cyclic citrullinated peptide antibody is positive, regular follow-up in the rheumatology clinic is needed to detect early rheumatoid arthritis. 3. According to the reference ranges provided by different hospitals and laboratories, whether the anti-cyclic citrullinated peptide antibody is within the normal range should be determined. If abnormal anti-cyclic citrullinated peptide antibody results are found, consultation with the local attending physician should be prioritized.