The great majority of physicians do not believe that there is such a thing as low DHEA. They argue that DHEA levels dramatically decrease with age, something I illustrate on my page DHEA Levels in Men by Age.and that a fall in DHEA is just a “part of life.” An additional argument is given that DHEA is precursor to many downstream hormones, including testosterone, estradiol, DHT, and that this is probably it’s primary role.
However, I will show below that DHEA is doing much more than just acting as a building block. In spite of these seemingly powerful arguments against DHEA Replacement Therapy, I want to give you the counterarguments to the above. Here are 4 Powerful Reasons You Don’t Want Low DHEA:
1. Increased Risk of Heart Disease. Low DHEA values have been linked to an increased risk of heart disease in us men..  This will almost always mean increased arterial plaque. Now the question always arises as to whether or not low DHEA values actually contributed to heart disease or were just an “innocent bystander,” i.e. a third party witness. The reason that this is very unlikely is that DHEA stimulates nitric oxide and even has a receptor in endothelial (arterial lining) tissue, something I discuss in page on the The Benefits of DHEA. In other words, low levels of DHEA will likely lead to decreased blood flow, which is almost always associated with increasing levels of atherosclerosis. And, as your arteries build up plaque, this creates a vicious cycle of less nitric oxide, less blood flow and so on. Many other thins that lower nitric oxide, such as homocysteine and PPI’s, are associated with accelerated cardiovascular disease.
2. Lowered Immunity. It is widely recognized that cortisol lowers immunity and DHEA boosts it.  Several studies to date have verified this in various forms. I find it difficult to imagine how low DHEA, which will help immune function, can possibly be a bad thing, especially in middle-aged and senior adults, whose immune system is already on the decline anyway to aging.
3. Increased Insulin Resistance. Animal studies had clearly shown that DHEA levels were tied to insulin sensitivity. In other words, as DHEA levels fall with aging, insulin resistance will tend to go up. This was verified in a recent study on seniors that found that administering DHEA decreased the insulin resistance of senior men (and women). Again, this is very reminiscent of what testosterone does for us.
4. Increased Mortality. If you put all these together, one can see just why DHEA should be part of most men’s anti-aging protocols, with powerful evidence being provided by the fact that lower DHEA-S levels are associated with an increased risk of dying:
“In men, most available evidence suggests an association with cardiovascular (CV) mortality rather than cancer mortality. Further, there are biologically plausible mechanisms for an effect of DHEA/-S on the development of CV disease.” 
Again, how can one argue that low levels of this key hormone are a natural and protective part of aging in light of the fact that low levels can lead to an eariler death?!
CONCLUSION: DHEA has an unusual history because about 20 years ago, it was touted as miracle anti-aging supplement and was literally thought to be a fountain of youth. However, then a couple of large followup studies put it against the ropes and suddenly DHEA found itself almost completely out of favor. It was seen for the most part as a harmless waste of money. However, now everything has come full circle and the last six years has seen just one study after another documenting the positive effects of DHEA supplementation and the very serious consequences of having low levels.
One recent reviewer made a nice summary by saying that “DHEA modulates endothelial function, reduces inflammation, improves insulin sensitivity, blood flow, cellular immunity, body composition, bone metabolism, sexual function, and physical strength in frailty and provides neuroprotection, improves cognitive function, and memory enhancement. DHEA possesses pleiotropic effects and reduced levels of DHEA and DHEA-S may be associated with a host of pathologies; .”  Yes, these words should remind you of the consequences the research laid out for standard hypogonadism (low testosterone).
3) Aging Cell,4(6):319 324, December 2005, “Raised cortisol:DHEAS ratios in the elderly after injury: potential impact upon neutrophil function and immunity”
4) J Steroid Biochem Mol Biol, 2015 Jan, 145:248-53, “DHEA and mortality: what is the nature of the association?”
5) J of Sexual Medicine, Nov 2011, 8(11):2960 2982, “Dehydroepiandrosterone (DHEA) A Precursor Steroid or an Active Hormone in Human Physiology (CME)