Men diagnosed with infertility have a higher risk of developing other general health ailments, including diabetes, ischemic heart disease, alcohol abuse and drug abuse, compared with fertile men, according to a study by researchers at the Stanford University School of Medicine.
The study, to be published online Dec. 7 in Fertility and Sterility, is one of several conducted by investigators at the medical school that suggest male infertility is associated with higher rates of mortality and health problems unrelated to reproductive health.
The study's lead author, Michael Eisenberg, MD, assistant professor of urology and director of male reproductive medicine and surgery at Stanford, hopes the findings will encourage more men diagnosed with infertility to seek follow-up care.
"For members of this group of reproductive-age men, they usually don't go to the doctor unless there is a big problem," Eisenberg said. "A lot of time fertility is one of the first things that brings them to the doctor, so in some ways that might be an opportunity to engage the health-care system and see what's going on with their general health."
Laurence Baker, PhD, professor of health research and policy, is the study's senior author.
Leveraging large databases
The researchers examined records filed between 2001 and 2009 of more than 115,000 reproductive-aged men from an anonymized insurance claims database. They analyzed the men's medical visits before and after fertility testing to determine what health complications they developed in the years after fertility evaluations. The researchers compared general health conditions of men with infertility diagnoses to men without the diagnoses and to vasectomized men.
Of the three groups, infertile men had higher rates of most diseases the researchers were screening for in the study, including heart disease and diabetes, even when results were adjusted for obesity, smoking and health-care utilization. In addition, men with the most severe form of male infertility had the highest risk of renal disease and alcohol abuse.
"It was surprising," Eisenberg said. "These were really young men. The average age was in the 30s."
Eisenberg and his colleagues are eager to pursue investigations to help determine why infertile men have a higher risk of certain diseases. "If we figure out why this is going on, we can target interventions to lower risks of these diseases," he said.
Mechanisms remain illusive
Researchers do not yet know why infertility is linked to higher rates of illness and mortality, but they have some theories.
Eisenberg noted that infertile men have lower levels of circulating testosterone than fertile men, a characteristic that has been linked to higher rates of mortality and cardiovascular disease.
Another possibility is that exposure to harmful environmental influences during fetal development could lead to both reproductive and general health challenges later in life. "Exposures that occur in utero can have lasting effects on the rest of your life," he said. "So maybe some of these same exposures that set men up later in life for things like heart disease could also set them up for things like lower sperm count."
Regardless of the reason, Eisenberg's research suggests that whatever is causing reproductive problems is likely to be influencing physiological systems, and he encourages men -- particularly men experiencing reproductive difficulties -- to get checked out.
"I think it's important to know that sperm counts and fertility may tell a little more than just about reproductive potential," he said. "There may be some other aspects that men could be alerted to about overall health."
Other Stanford co-authors of the study are statistician Shufeng Li and and Mark Cullen, MD, professor of medicine.
Stanford's departments of Urology, of Dermatology and of Health Research and Policy supported the work.
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