The blood level of hyaluronic acid (HA), a lubricating substance within cartilage and the synovial fluid in joints, may be a useful biomarker signaling the presence and severity of osteoarthritis, according to research recently funded by the National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS).

Joanne Jordan, M.D., M.P.H., and her colleagues at the University of North Carolina Chapel Hill and Duke University, learned that there was a strong association between HA blood level (serum HA) and increasing OA severity as measured by X-ray of the knees and hips. Additionally, regardless of disease severity, serum HA was generally higher in men compared to women, and in Caucasians compared to African Americans.

X-rays and blood tests from 753 study participants from a larger study of osteoarthritis (the Johnston County Osteoarthritis Study) were the basis for this study. The researchers examined the relationship of serum HA to several factors: X-ray evidence of osteoarthritis, age, gender, race, body mass index (BMI) and various self-reported coexisting disease conditions (particularly circulation problems, cancer, gout, high blood pressure, diabetes and rheumatoid arthritis).

The scientists noted that of the possible coexisting conditions, only gout was found to have an independent association with serum HA. They believe this is due to the degree of joint inflammation and damage caused by gout. They also suggest that gender and ethnicity need to be considered in the study of biomarkers for OA, and more research is needed to explore what underlies the finding of higher serum HA in men and in Caucasians.

Osteoarthritis, also known as degenerative joint disease, is the most common type of arthritis in adults, and is characterized by cartilage breakdown in the affected joints. X-rays are currently used to diagnose osteoarthritis and monitor disease progression, but it is thought that molecular biomarkers could provide a better way to detect disease activity. Changes in a joint may not be visible by X-ray for 1 to 3 years after they occur. Tests that recognize the presence of biomarkers will help doctors identify early signs of disease, more reliably detect disease progression, and assess patient response to treatment.

Other supporters of the study included the National Institute on Aging, the Centers for Disease Control and Prevention/Association of Schools of Public Health and the Arthritis Foundation.

The National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS) is part of the U.S. Department of Health and Human Services' National Institutes of Health, the leading Federal agency in biomedical and behavioral research. The mission of NIAMS is to support research into the causes, treatment, and prevention of arthritis and musculoskeletal and skin diseases, the training of basic and clinical scientists to carry out this research, and the dissemination of information on research progress in these diseases. For more information about NIAMS, call the information clearinghouse at (301) 495-4484 or (877) 22-NIAMS (free call) or visit the NIAMS Web site at

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Jordan JM, et al. Serum hyaluronan levels and radiographic knee and hip osteoarthritis in African Americans and Caucasians in the Johnston County Osteoarthritis Project. Arthritis and Rheumatism 2005;52(1):105-111.

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