As many of you know, the pharmaceutical manufacturers of testosterone have been under fire. I even have a page covering the Testosterone-Related Class Action Lawsuits that surfaced last year. The lawsuits center around a couple of studies where men on HRT were allegedly found to have increased risk of cardiovascular disease. These studies always floored me, because testosterone is so pro-heart in my opinion, showing that well done HRT tends to unharden arteries, lower arterial inflammation, lower insulin resistance, lower visceral fat, decrease the risk for diabetes and prediabetes and improve a guy's sex life. All of these should add up to improved cardiovascular outcomes, not the other way around. These are all things I document in my book Low Testosterone by the Numbers. And, sure enough, a couple of follow up studies showed lowered cardiovascular risks for men on HRT.
UPDATE: I also highly recommend that one read these important pages for other very important research on the subject: Testosterone Therapy and the Recent VERY Postive Research and Profound Lowering of Cholesterol in Men through HRT.
I am not going to get into the debate on cardiovascular risk on this page. However, here I do want to show yet another risk factor for heart disease that testosterone alters positively in almost all of the studies that I have seen: total cholesterol and LDL. As I will show, most of the research shows HRT pushing both of these bad boys down. Now I know that some of you are convinced that high cholesterol and LDL are actually good for you. To that I can only point out that all the Plaque Reversers Require Low Levels of LDL and Total Cholesterol.
Here are the Key Lines of Evidence that Testosterone is Critical for Cholesterol Management:
1. Testosterone Undecanoate. One study looked at testosterone undecanoate, which is the injectible testosterone ester in Nebido and Aveed, and concluded that "there were parallel declines in plasma total cholesterol, LDL, and triglycerides, whereas plasma HDL showed a parallel rise. The magnitude of these changes was greater with TU than with T gel."  Basically, it was everything a cardiologist could hope or dream for! Notice that both the topical testosterone and the testosterone undecanoate exhibited these properties, but undecanoate was the winner. Why is that? The authors also point out that the testosterone undecanoate gave them higher testosterone levels, so one could argue that more testosterone resulted in greater cholesterol control. Below we will show you another study that indicates this.
CAUTION: As I mentioned above, there are some studies out there that show that TRT can lower the "good cholesterol," something I cover in my page on Testosterone and HDL. Researchers believe this may have to do with the type of testosterone given and perhaps the values at baseline.  The smart thing to do is to pull your lipids before and after and actually monitor yourself. And lab prices have really dropped recently: check out my page on Inexpensive Labs for Self-Testing.
2. 2005 Research Review. One study looked over all the past studies and did its best to statistically aggregate the results. The researchers found that, in general, testosterone therapy reduced total serum cholesterol, although they also concluded that it did not statistically change LDL.  There are studies that have found no change in cholesterol.  However, these researchers tried to pool results and did not look at just one isolated study. Now the fact that the above research review found no net decrease in LDL may sound rather damning. However, check out the study in #3 before you come to any conclusions!
3. Long Term Study. Virtually all studies on testosterone therapy are quite short term actually - I am sure due to funding reasons for the most part. However, one testosterone study on hypogonadal men found huge significant and consistent drops in LDL and total cholesterol for five years. They patients were given Nebido, i.e. testosterone undecanoate and essentially doubled their total testosterone levels.
Here is the Mescape summary as to what happened:
"They also examined whether testosterone affects the components of the metabolic syndrome. Testosterone treatment resulted in a gradual and consistent decline in total-cholesterol levels, which was significant as early as 12 months of therapy and reached a plateau at 24 months. At baseline, the mean total cholesterol was 7.3 mmol/L (282 mg/dL), and this was reduced to about 4.9 mmol/L (188 mg/dL) by 24 months of therapy, remaining low throughout the remaining period of therapy. Similarly, there were marked and significant gradual and consistent decreases in LDL-cholesterol levels, from 4.2 mmol/L (164 mg/dL) to 2.8 mmol/L (110 mg/dL), significant within the first year of treatment and at 24 months and stable thereafter over the course of the 5-year period." 
These are huge drops in cholesterol and LDL if you'll notice! Furthermore, the researchers pointed out that the results just kept getting better and better. Even if we keep in mind that these men started with very high average cholesterol and pretty nasty lipid profiles, the results are impressive and point out that testosterone can do some very impressive health-promoting things if you give it time and, of course, provide the patient with a decent protocol.
Did you know you can inexpensively do your own testing for most hormones? The industry leader is Discounted Labs..
CAUTION: High estradiol from overly aggressive TRT could potentially increase a proclivity toward clotting for men with an actual clotting disorder, something I discuss in my page on Some Potential Dangers with TRT Injections. Some studies also show that TRT can lower the "good" cholesterol: see Testosterone and HDL for more information. Hopefully, more study work will follow.
4. Low Testosterone Leads to High Cholesterol! A literature review found that "Testosterone therapy has beneficial and deleterious effects on cardiovascular risk factors. It improves insulin sensitivity, central obesity, and lowers total cholesterol and LDL."  The authors went on to point out that "hypogonadism is associated with central obesity; insulin resistance; low levels of high-density lipoprotein (HDL); high cholesterol levels; and high levels of low-density lipoprotein (LDL), triglycerides, fibrinogen, and plasminogen activator 1."  So this is another case where low testosterone does not look so good for the heart!
5. Testosterone Suppression Raises Cholesterol. One study pharmaceutically suppressed the testosterone of eight men to nearly castrate levels and - you got it - cholesterol rose from an average of 177 to 208, a 17.5% increase.  NOTE: HDL, the "good cholesterol" also increased.
CAUTION #2: You do not want to go too high in testosterone, something I discuss quite often in the Peak Testosterone Forum. First of all, steroid men often have greatly skewed lipids and high cholesterol. However, there was also a study done where researchers gave healthy men 200 mg of testosterone enanthate per week. Enanthate is quite similar to the cypionate ester and 200 mg per week is a beefy dose. So these men did not really need probably HRT and they gave them a large dose. And, even though the men were not taking steroid levels, they experienced no beneficial changes in cholesterol and a significant decrease in HDL. Again, the body is a highly tuned machine and it is very difficult to push physiological ranges successfully.
1) A Dose-Response Study of Testosterone on Sexual Dysfunction and Journal of Andrology, Jan-Feb 2008, 29(1):102 105, January-February 2008"Features of the Metabolic Syndrome Using Testosterone Gel and Parenteral Testosterone Undecanoate"
2) The American Journal of Cardiology, Dec 2005, 96(12 Supp2):67 72, "Cardiovascular Issues in Hypogonadism and Testosterone Therapy"
3) Clinical Endocrinology, Sep 2005, 63(3):280 293, "Effects of testosterone on body composition, bone metabolism and serum lipid profile in middle-aged men: a meta-analysis"
4) JCEM, Published Online: Jul 01 2013, "Pharmacokinetics of Transdermal Testosterone Gel in Hypogonadal Men: Application of Gel at One Site Versus Four Sites: A General Clinical Research Center Study"
5) Medscape Medical News, "Five Years of Testosterone Ameliorates Metabolic Syndrome in Hypogonadal Men", Lisa Nainggolan, October 28, 2013
6) JCEM, Published Online: Jul 01 2013, "Suppression of Plasma Testosterone Leads to an Increase in Serum Total and High Density Lipoprotein Cholesterol and Apoproteins A-I and B"