Metabolism refers to the chemical reactions in your body's cells that let you get or use energy from things like food. Metabolic diseases interfere with that process.
The study looks into whether infertility, in men under 50 years old, could help doctors predict whether they'll get such diseases down the road. The research appears in the journal Clinical Endocrinology.
About 15% of all couples contend with infertility, and about half the time, it's due to the man being infertile. Past studies have shown an unexplained link between men with poor semen quality and a lower life expectancy.
"There is a significant need for more studies in this field," says University of Copenhagen Professor Jens Sønksen in a statement from the European Association of Urology 2016 Congress in Munich, where the new research was presented.
Low Sperm Counts
It’s unclear to what degree young men with fertility problems have signs of low testosterone levels (also called "hypogonadism"), say Johannes Bobjer, of Skåne University Hospital and Lund University in Sweden, and colleagues. It’s also not clear whether low T is linked to a risk for osteoporosis and metabolic problems, as it is in older men.
To examine this issue, researchers studied 192 men ages 18 to 50 with a low sperm count, and compared them with an age-matched group of 199 other men.
They compared sex hormone levels and other signs, such as bone mineral density and blood sugar levels.
Low testosterone levels were 10 times higher among the men with fertility problems than among those in the control group.
A third of men with fertility problems and low T were found to also have higher blood sugar levels and lower bone mineral density in the lumbar spine compared to those with normal testosterone levels.
Men with low T also had higher triglycerides (a type of fat found in the blood), signs of insulin resistance, and an increased risk of metabolic syndrome, compared to men with fertility problems but hormone levels in the normal range.
Since the study showed that men with fertility problems were more likely to have low testosterone, "all men with fertility problems and any unusual signs in semen quality should have their [reproductive] hormones checked” at their first visit to a fertility specialist, says researcher Aleksander Giwercman of the Reproductive Medicine Center at Skåne University Hospital.
But he stopped short of saying testosterone therapy is needed to avoid a metabolic disease. That treatment should be avoided as long as a couple is receiving treatment for infertility, since receiving testosterone may also suppress sperm production, he says. What's more, it hasn’t been proved that testosterone therapy can lead to improvement for metabolic issues and bone mineral density.
Giwercman says his team would like to keep tabs on the men in the study to see whether their symptoms get worse without treatment.
What About Older Guys?
Research shows a link between low testosterone and problems such as metabolic syndrome, type 2 diabetes, cardiovascular disease, and osteoporosis in older men, but the causes aren't well-understood by scientists -- and the issue of testosterone treatment is the subject of much controversy.
"Some studies suggested that low testosterone is merely a marker [or sign] of poor general health in elderly men," the researchers behind the new study write.
Giwercman says doctors may be reluctant to start testosterone therapy in older men because of the uncertainty regarding the risks, but he recommends the treatment if a man’s testosterone levels are really low and he has no conditions, such as prostate cancer, that may complicate the treatment.