Hydroxyproline as a New Biomarker to Differentiate Osteoarthritis from Rheumatoid Arthritis in the Early Stages

Abstract

Background: Osteoarthritis (OA) and rheumatoid arthritis (RA) are the most common inflammatory disorders of the musculoskeletal system which are defined by articular cartilage degradation and impairment of joint. When criteria and radiography are insufficient to diagnose early-stages of RA and OA to control disease course, biomarkers become necessary to early diagnosis these diseases.Objective: We searched the levels of (MMP3) and (HP) in the blood of early RA and OA patients in order to see if they can be utilized to distinguish the two diseases at an early stage.Patients and Methods: We recruited 1) forty patients who were diagnosed with early knee osteoarthritis using EULAR and Kellgren-Lawrence radiographic grading criteria, 2) forty patients with early RA (disease duration less than three years), and 3) forty control group consisted of normal volunteers who were age and sex matched. All subjects underwent a thorough medical history, clinical musculoskeletal examination, and laboratory tests, including the determination of blood MMP3 and HP. We did also a simple x-ray of their hands and knee joints.Results: Comparing groups, we found a highly significant increase in serum MMP3 in OA patients than RA patients and control groups. MMP3 was also significantly higher in RA patients than in the control group. While, OA patients had significantly higher HP than RA patients and control groups, whereas RA patients and control groups had no significant difference in HP.Conclusion: Hydroxyproline rather than MMP3 may be employed as a potential biomarker for early differentiation between osteoarthritis and rheumatoid arthritis.