Here are some of the studies showing Statins Lower Testosterone But Probably Not By Much:
1. Meta-analysis. One large meta-analysis looked at many studies and found that men with high cholesterol, on average, lost 0.66 nmol/l or about 20 points (in ng/dl) of testosterone. Now this isn’t much of a drop, so the question is if it could cause issues when coupled with other effects of statins.
2. REBUTTAL: Not With Controls. In fairness to good doctors like Dr. Gould, who often use statins to regress arterial plaque, I want to mention that a 2007 study found that if you controlled for things like age, BMI, time of day (for the blood draw), etc. the drop was only 5.5%.  Of course, every molecule is precious, eh? But let’s be honest and admit that one is very unlikely to notice a drop from, say, 500 ng/dl to 475.
3. Lowered Aggressiveness and Disrtubed Sleep. Now let’s go to what is probably the most relevant aspect of statin use: their ability to sometimes product “low testosteorne symptoms.” For example, one study found that men had lowered levesl of agressiveness on statins and speculated that it was from the lowered testosterone levels.  The authors explained that:
“For men, the picture was more complex. Three male participants who took statins (and no one on placebo) displayed very large increases in aggression. When these were included in analysis, there was no average effect. When these outliers were removed from the analysis, a decline in aggressive behavior for male statin users was significant.” 
Now, assuming that testosterone is actually lowered by very small amounts actually, this is a bit of stretch. And the researchers in the same study explained that “changes in testosterone and in sleep problems on simvastatin each significantly predicted changes in aggression. A larger drop in testosterone on simvastatin was linked, on average, to a greater drop in aggression.
Thus sleep and other brain changes are probably the real culprit. Notice that the researacher mentioned simvastatin specifically. As I explain in my page on The Dangers and Risks of Statins, some of these medications are much more lipid soluble than others. And the significance of being lipid soluble is that they penetrate the blood brain barrier easily and can, apparently, have undesireable consequences. Simvastatin (Zocor) is very lipid soluble. Yeah, you didn’t read that in fine print, did you?
CONCLUSION: So what should you do? Should you trust these studies and assume your testosterone may go down a little but not by much? My opinion is that you should measure your testosterone before and after any change and see for yourself. Studies deal with averages, and what if you are an outlier? Here in the U.S., they are multiple labs where you can pull testosterone inexpensively without a direct doctor’s orders, so just do it: Inexpensive Testosterone Labs.
NOTE: Statins can have one positive effect: improved erectile and endothelial function. One study note a quite significant improvement in erectile dysfunction from taking statins in older men, and this is undoubtedly due to higher cholesterol levels that plaque arterial blood flow to and within the penis.  However, I would argue that there is a much better and safer to lower cholesterol levels and improve erectile function for many men and that is through a well done, whole foods, good carb low fat diet. Low fat diets will almost always drop your cholesterol very significantly and, if you do it right, can actually lower triglycerides. See my page on The Benefits of a Low Fat Diet for more information. Remember that statins go in and interfere with the enzyme that creates CoQ10. Low fat diets do NOT. Furthermore, one does not have to worry about crossing the blood-brain barrier with the whole foods that are emphasized in a low fat diet.
1) BMC Med, 2013 Feb 28, 11:57, “The effect of statins on testosterone in men and women, a systematic review and meta-analysis of randomized controlled trials”
2) Cancer Epidemiol Biomarkers Prev, August 2007, 16:1587, “Do Statins Affect Androgen Levels in Men? Results from the Boston Area Community Health Survey”
4) U.S. San Diego News Center, July 01, 2015, By Scott LaFee, “Statins Linked to Lower Aggression in Men, but Higher in Women”