Growth factors, insulin-like growth factor-1 and growth hormone, in synovial fluid and serum of patients with rheumatic disorders

Objective: Synovial fluid (SF) plays an important role in joint function. We evaluated the growth factors, insulin-like growth factor-1 (IGF-1) and growth hormone (GH) in SF and serum from patients with osteoarthritis (OA), rheumatoid arthritis (RA), gout, pseudogout and diffuse idiopathic skeletal hyperostosis (DISH). Design: Standard radioimmunoassay techniques were used to measure concurrent levels of IGF-1 and GH. SF samples and serum samples were obtained concomitantly from 27 patients with OA, 22 patients with RA, nine men with gout, 14 patients with pseudogout and eight men with DISH. Results: In the case of IGF-1, a comparison of serum and SF levels shows that SF levels of IGF-1 are lower than serum levels in all groups. Men and women gave similar values. In contrast, in the case of GH, all groups, except males with RA, had higher GH values in SF when compared with serum values. Individual patients with other forms of arthritis demonstrated similar relationships. Conclusion: The finding that IGF-1 is present in levels about one-half as great in SF as compared with serum suggests that IGF-1 may be produced in lesser amounts or is utilized by the patient in customary joint function. The finding that GH is present in SF at values twice as high, or more, of serum levels in inflammatory arthritides suggests that GH may play a role in the pathophysiology of arthritic disorders.