(HealthDay News) – Hormonal changes, especially testosterone, precede the onset of rheumatoid arthritis (RA) in men and may influence the type of RA, according to research published online April 3 in Annals of Rheumatic Diseases.

Mitra Pikwer, of Lund University, Skane University Hospital, in Malmo, Sweden, and colleagues designed a nested case-control study to determine the relationship between reproductive hormone levels and the development of RA in men. Blood samples from a population-based health survey were analyzed for testosterone and other reproductive hormones, and results were linked to clinical data obtained from local and national registers.

According to the researchers, among the 104 cases of RA identified, 73% were rheumatoid factor (RF) positive. After adjustment for smoking and body mass index, lower levels of testosterone were significantly associated with development of RF-negative RA (odds ratio [OR], 0.31 per standard deviation), but not significantly associated with RF-positive RA (OR, 0.87; 95% confidence interval, 0.53–1.43). Follicle-stimulating hormone levels increased in patients prior to the development of RF-negative RA (P=0.02), but decreased in patients prior to RF-positive RA (P=0.02).

“We report a negative association of testosterone and free testosterone levels with the risk of developing RF-negative RA in men,” the authors write. “Since this is the first major study of testosterone and related hormones in the preclinical phase of RA, our findings should be verified in other populations.”

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