The purpose of the study is to determine whether plasma levels of the collagen triple helix repeat containing (CTHRC1) protein can serve as a blood-based biomarker for diagnosis of rheumatoid arthritis (RA) ,and furthermore its correlation with disease activity.

Rheumatoid arthritis (RA) is a chronic, progressive, autoimmune disease of synovial joints. Characterized by periods of flares with high disease activity involving both a systemic immune response and tissue-specific inflammatory events that can lead to erosive joint and bone destruction and subsequent disability . Currently, diagnosis of RA is based mainly on the extent of tenderness and swelling of the joints , levels of acute-phase reactants such as C-reactive protein (CRP) ,erythrocyte sedimentation rate(ESR) , high titers of rheumatoid factor (RF) and high titers of antibodies against cyclic citrullinated peptide (anti-CCP) in the plasma .Of interest, CTHRC1 is a secreted modulator of Wnt signaling, which is a key regulator of joint remodeling, and promotes cell proliferation and migration. Therefore, CTHRC1 may contribute to multiple aspects of the pathogenic FLS behavior in RA and modulate processes that promote synovial hyperplasia and invasion.The expression pattern of CTHRC1 in pannus, its role in the function of FLS relevant to cartilage damage in RA, and CTHRC1's association with disease severity in murine arthritis raised the question of whether CTHRC1 could be used as a marker for RA diagnosis and monitoring of disease activity in patients

Inclusion Criteria:

• -Patients diagnosed as RA.
• Patients ( >18)who are age and sex matched with the controls

Exclusion Criteria:

. Other Rheumatologic diseases. .Patients with malignancy . .Patients with hepatic disease .

measurement of CTHRC1in RA patints