Persistent high cholesterol levels cause heart disease. Hmg-coa reductase inhibitors, commonly known as statins, lower high cholesterol levels. As of 2010, several small studies have examined how statins affect testosterone levels in men, with some studies showing a significant decrease in testosterone levels, and others showing no difference at all. Results from a study presented at the European Congress of Endocrinology in 2010 showed a reduction in the percentage of live sperm cells but didn't show any effect on testosterone levels. Further research and larger studies are needed to understand the exact affect statins have on testosterone levels in men.
Reduced Testosterone
The leydig cells, found in the testicles, produce testosterone. These cells get cholesterol in two ways: they absorb it from the blood or make it themselves. Research published in the "British Journal of Clinical Pharmacology" shows that statins can interfere with the synthesis of testosterone in three ways. The most common theory is that statins decrease male fertility by lowering the amount of cholesterol in the blood. The leydig cells absorb cholesterol from the blood and use it to produce testosterone. If these cells can't get enough cholesterol, they can't make the required amount of testosterone needed by the body.
Statins in the Testes
Even though statins work mainly on the liver, research shows that small quantities of statins have been found in the testes of men on statin therapy. These small levels of statins in the testes directly prevent the leydig cells in the testes from making testosterone on their own.
Simvastatin
High doses of simvastatin, and possibly other statins, directly suppress human testosterone synthesis. Simvastatin directly inhibits an enzyme which stimulates the conversion of dehydroepiandrosterone to testosterone. This reduction in testosterone was shown to be significant; however, the reduction didn't affect male fertility in any way. The high dose of simvastatin required to directly suppress testosterone synthesis would be contraindicated for normal cholesterol reduction in patients.
