Testosterone first became available in the 1930s, but it is only over the last 15 years or so that there has been much experience with it. I began my research with testosterone in 1975, working in the laboratory of David Crews, PhD, at Harvard University, as an undergraduate. When I graduated from urology residency in 1988, testosterone use as a medical therapy was rare, limited almost without exception to those few cases where men had lost their testicles to trauma or cancer, or to men with pituitary tumors.
The idea that a man with normal testicles and pituitary could experience symptoms from low levels of testosterone was almost unknown, and there was negligible experience treating these men with testosterone. Today, of course, this is the most common scenario we see.