''Current statin therapy is associated with a twofold increased prevalence of hypogonadism," a condition in which men don't produce enough testosterone, study author Giovanni Corona, MD, PHD, a researcher at the University of Florence in Italy, tells WebMD.
Although previous studies have produced mixed findings on the possible link between taking cholesterol-lowering drugs and a drop in testosterone, most involved a limited number of patients, with few studies including more than 50 people, Corona says.
"Our study is the first report showing a negative association between statin therapy and testosterone levels in a large series of patients consulting for sexual dysfunction," he says.
About one of six adults in the U.S. has high cholesterol, according to the CDC. The number of people buying a statin (such as Lipitor or Zocor) rose 88% from 2000 to 2005, from 15.8 million people to 29.7 million, according to the federal Agency for Healthcare Research and Quality.
Statins, Testosterone, and ED: The Study
Corona and colleagues evaluated 3,484 men, average age 51, who visited an outpatient clinic at the University of Florence with complaints of sexual dysfunction between January 2002 and August 2009.
The researchers calculated the men's total testosterone as well as free testosterone, the amount of unbound testosterone in the bloodstream.
When they compared men on statins to those not, the men on statins were twice as likely to have low testosterone, regardless of which of three commonly used thresholds for low testosterone they looked at.
The researchers emphasize they have found a link, not a cause and effect, between statins and lower testosterone. They can't explain the link with certainty.
One possibility, Corona says, is that low testosterone levels and the need for statin treatment share some common causes.
Some researchers also have looked at the possibility that the statins' inhibition of cholesterol synthesis may interfere with the production of testosterone, which depends on a supply of cholesterol. The statins may disrupt the body's feedback mechanism to instruct it to make more testosterone.
Statins, Testosterone, and ED: Other Views
''This is huge," says Irwin Goldstein, MD, director of sexual medicine at Alvarado Hospital in San Diego and editor-in-chief of the Journal of Sexual Medicine.
The study results, he says, demonstrate the need for more study to replicate the finding and figure out the reason for the link.
According to the authors, he says, the best explanation for now is that "statins may disrupt the pituitary feedback to the testicles, telling them to produce testosterone."
For consumers, he says, the message is for men on statins to pay attention to early warning signs of testosterone deficiency. That includes falling asleep after meals when they did not in the past, noticing poorer athletic performance, having a change from an upbeat mood to a grumpy mood, and experiencing a reduced sex drive, Goldstein says.
If a man suspects testosterone deficiency, Goldstein says he should ask his doctor about checking his testosterone levels.
Statins and Testosterone: Industry Input
In a prepared statement, Sally Beatty, a spokeswoman for Pfizer, the manufacturer of Lipitor, says, "Millions of people have been prescribed Lipitor, which is clinically proven to lower bad cholesterol levels 39%-60% (this is an average effect depending on dose), when diet and exercise aren't enough."
The label on Lipitor does warn of the possibility of interference with hormone production, she says. "As described in the Lipitor U.S. prescribing information, statins interfere with cholesterol synthesis and theoretically might blunt adrenal and/or gonadal steroid production."
But she says, "It is important to note that some other studies and analyses have shown that Lipitor does not have an effect on levels of testosterone or other reproductive steroid hormones."