By Rachael Rettner, Senior Writer
Published: 07/31/2013 09:19 AM EDT on LiveScience
Men with large testicles may be at increased risk of heart disease, and a new study from Italy suggests why.
The study measured the testicle size of more than 2,800 Italian men who sought care for sexual dysfunction, and were followed for about seven years afterward.
Unexpectedly, the researchers found a link between risk factors for heart disease -- such as obesity, smoking and high blood pressure -- and larger testicles.
Having larger testicles was also linked with a slightly increased risk of being hospitalized for heart disease, which could be due to the risk profile of men with larger testes, the researchers said.
The researchers also found a link between high levels of luteinizing hormone (LH) -- which is secreted by the pituitary gland, and stimulates production of testosterone -- and an increased risk of heart disease. This link held even after the researchers took into account risk factors for heart disease.
It's possible that high LH levels may have a direct, harmful effect on the cardiovascular system, or that another factor not considered in this study is responsible for both high LH levels and heart disease, the researchers said.
Previously, larger testicles were considered a sign of good reproductive health, so it was surprising to find a link between large testicles and poor health, the researchers said.
"Although it is generally assumed that testis size can predict reproductive fitness, our results indicate that this objective parameter can provide insights also on overall health and [cardiovascular disease] risk," the researchers wrote in the July 11 issue of the Journal of Sexual Medicine.
As for the reason that larger testicles may be linked heart disease, the researchers pointed to the fact that men with health problems, such as diabetes and heart disease, are known to have lower testosterone levels. The researchers speculated that, in such men, the body may try to compensate for low testosterone levels by secreting higher levels of pituitary hormones, which in turn could lead to an increase in testicle size.
However, other experts called his hypothesis a stretch.
Although men with low testosterone might have an increase in the production of pituitary hormones, the notion "that then the testicle gets pushed by the pituitary, and gets bigger than normal -- I doubt that's true," said Dr. Andrew Kramer, a urologist at the University of Maryland Medical Center.
"I suspect testicular size isn't any bigger, but maybe smaller than their healthy counterparts," Kramer said.
Kramer agreed that high LH levels are a sign of poor health, and could be linked to heart problems. But he said he would have expected low LH levels to be linked with bigger testicles, and high LH to be linked with smaller testicles. "I think there isn't a relationship that makes sense here," Kramer said.
Because the study was conducted on men with sexual dysfunction, the results may not apply to the general population, the researchers said.