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Connecting the dots between common male medical condition and later disease

Cardiac, metabolic and vascular disease are often hard to catch in their early stages, but Stanford researchers may have identified a risk factor to help physicians spot them.

“It can make a big impact if we can find a sign, early on, that patients have significant risk of developing these diseases,” said Nancy Wang, MD, a resident in urology and the lead author of a recent study.

A team led by Wang and senior author Michael Eisenberg, MD, analyzed thousands of medical insurance records and spotted a connection between a common male medical condition and metabolic and vascular disease.

The condition, known as “varicoceles,” affects about 17 million men in the United States — roughly 15 percent of the total population. Varicoceles are similar to varicose veins, but are located in the scrotum. These dilated veins allow extra blood flow through the scrotum and raise its temperature. The increased heat can lower sperm and testosterone production and sometimes lead to infertility.

Low testosterone also plays a role in conditions other than infertility, including heart disease, diabetes and hyperlipidemia. Eisenberg connected the dots and began to wonder if varicoceles put men at higher risk for these diseases by lowering their testosterone levels.

“We’ve showed that infertile men seem to have higher risks of some diseases than other men and the question is always why?” said Eisenberg. “If we can understand who is at risk, we can mitigate that risk through targeted screening or by following up certain individuals a little closer.”

The researchers harnessed the power of big data to investigate the connection between varicoceles and later disease, according to the study’s press release:

For the study, Eisenberg’s lab dug through a wealth of data housed in the Truven Health Marketscan Commercial Claims and Encounters database, which contains insurance claims filed by 77 million individuals since 1996. Between 2001 and 2009, the researchers identified more than 4,400 reproductive-age men with diagnosed varicoceles. For comparison, the team also looked at men without varicoceles — a group that included both infertile and fertile men, differentiated based on whether they had received infertility screening or a vasectomy.

Compared to men without varicoceles, men with the condition had a significantly higher incidence of heart disease, the researchers found. They also had a higher incidence of diabetes and hyperlipidemia, or high concentrations of fat in their blood.

But not all cases of varicoceles have this associated risk, said Eisenberg.

Some men with varicoceles experience fertility issues and pain, but millions show neither of these symptoms. According to the study, these asymptomatic cases are not associated with an increased risk of metabolic or vascular disease. Because their varicoceles aren’t causing problems, asymptomatic patients typically go untreated and are simply monitored over time. The results suggest that this remains a viable management strategy, Eisenberg said.

The researchers stress that there is a correlation between varicoceles and other diseases, but its exact mechanisms are unknown. To better characterize the link, Eisenberg and his team are diving back into the data.

“This condition is a really common entity, and here is this association we haven’t been able to see before,” said Eisenberg. “By working with this big data revolution and taking advantage of these large data sets, we can find these smaller trends.”

Previously: Male infertility linked to host of other ailments, How can we get men to take better care of themselves and Average U.S. newborn's dad is getting older (as is mom) — and it matters
Image by Quinn Shanahan

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