I think that this question has already been answered and probably more than once.
DHT is an abbreviation for dihydrotestosterone.
Your testicles and your liver both produce testosterone. The problem is that testosterone has to be broken down in order to be utilized for the many purposes it serves. The liver secretes what is called a specialized enzyme that modifies testosterone. That enzyme is called 5-alpha-reductase. This takes testosterone and divides off a second compound.
Where standard testosterone has many effects on metabolism, DHT and all of it's effects are mainly centered on your secondary sex characteristics and maintenance of your sex drive and performance.
Your body can produce testosterone by the gallon and if you do not produce 5-alpha-reducatase you as a male will never go through puberty. It is the DHT that completely deals with your genitalia and sex development as a teen, and as an adult even your sex life.
DHT has been totally demonized by the hair regrowth industry. They do this to create a demon to sell their wares. DHT does not cause male pattern baldness in and of itself. DHT can contribute to male pattern baldness if you are genetically predisposed to it. If you're not, all the DHT on the planet will not cause YOU to lose your hair. Propecia and other drugs which prevent the conversion of of testosterone to DHT by interfering with the action of 5-alpha-reductase on the other hand have a very high track record of causing erectile dysfunction and in some men even gynecomastia (male breast growth).
There is new research out of Europe which is even placing some doubt on the role of DHT as a singular influence in prostate growth (BPH) and the spread of prostate cancer.
