(RxWiki News) Low testosterone can affect a man's life in many ways, from reduced sex drive to lack of energy. Now it seems low levels of this hormone may be related to joint disease.
Results from a recent study showed that men with lower levels of testosterone may be more likely to develop rheumatoid arthritis in the future.
However, these findings should be interpreted with caution, particularly because testosterone levels were not all that different between men who went on to develop rheumatoid arthritis and those who did not.
"Tell a doctor if your sex drive has slowed down."
Past research has shown that men with rheumatoid arthritis tend to have lower testosterone levels than those without the condition. However, it has not been known whether these hormonal changes happen before the disease develops.
To address this unknown, Mitra Pikwer, MD, of Lund University in Sweden, and fellow researchers identified men with rheumatoid arthritis from a large health survey called the Malmo Preventive Medicine Program (MPMP), which tracked the health of more than 33,000 people starting in 1974. MPMP participants underwent a number of tests, filled out questionnaires and had blood samples drawn.
From this study population, Dr. Pikwer and colleagues were able to look at blood samples of 104 men who went on to develop rheumatoid arthritis and 174 matched controls (men of the same age who did not develop rheumatoid arthritis). The researchers used these blood samples to measure levels of testosterone and other sex hormones, including follicle-stimulating hormone (FSH), luteinizing hormone (LH) and sex hormone-binding globulin (SHBG).
The aim of the study was to see if differences in hormone levels between healthy patients and arthritis patients could be spotted years before those arthritis patients were diagnosed.
Among participants who went on to develop rheumatoid arthritis, the time between giving a blood sample and diagnosis ranged anywhere between one and 28 years.
Researchers had the rheumatoid factor (RF) status at time of diagnosis of 83 men who went on to develop rheumatoid arthritis. Of these, 73 percent tested positive for RF.
RF is a protein made by the immune system. High levels of RF have been associated with rheumatoid arthritis. However, RF can be detected in healthy people, and people with rheumatoid arthritis can have normal levels of the protein.
Study results showed that lower levels of testosterone were linked to higher odds of developing rheumatoid arthritis, specifically RF-negative rheumatoid arthritis. However, this association only seemed apparent after accounting for other factors that increase the risk of rheumatoid arthritis, including smoking and obesity.
The researchers found only small differences in testosterone levels between men who developed rheumatoid arthritis and those who did not. Testosterone levels ranged from about 20 nmol/l to about 22 nmol/l.
While these differences may be significant in a study setting, they may mean little in a clinical setting.
In a previous paper on a similar topic, Dr. Pikwer highlighted this issue: "The differences in testosterone in pre-RA men noted in our material were only apparent in models adjusted for relevant confounders. This makes it more complicated to measure testosterone as a predictor of RA in the clinical situation."
Except for one other small study from Finland, "this is the first study to explore hormone levels in men before rheumatoid arthritis diagnosis," the authors wrote.
In conclusion, they wrote, "Since this is the first major study of testosterone and related hormones in the preclinical phase of rheumatoid arthritis, our findings should be verified in other populations."
The study was published in April in the Annals of the Rheumatic Diseases.
The research was supported by the Swedish Research Council, the Swedish Rheumatism Association, Lund University and the County of Skåne. The authors declared no competing interests.