When a man uses synthetic forms of testosterone (all anabolic steroids are derivatives of testosterone), the hypothalamus responds by
halting the body's testosterone- synthesizing process. One side effect of this mechanism, even from conservative or therapeutic doses
of testosterone, is the precipitous decline of sperm production after about two weeks. For this reason, testosterone is under serious
consideration by the World Health Organization for use as a male contraceptive.
Sperm production begins anew if the testosterone injections are discontinued, and it is usually restored to normal levels when the hormone has completely cleared the body. Whether sperm production is fully restored, however, ultimately depends on the duration of the testosterone injections and the individual subject's response.
Athletes commonly use dosages of steroids that are 10-40 times greater than the suggested therapeutic range. This theoretically places these men at risk of side effects related to long-term testosterone inhibition, a medical condition known as hypogonadotropic hypogonadism. Indications of this disorder include shrunken testicles, impotence and, most commonly, infertility.
Should athletes who inject testosterone worry about infertility? To some degree, yes. Since the probability of inducing pregnancy depends on a certain number of active sperm, depletion of sperm due to long-term or high-dose steroid use could ruin an athlete's hopes of fathering children.
That, however, is a worst-case scenario. While the possibility of permanent infertility always looms over heavy steroid users, it is something of a rarity in real life. The plethora of former anabolic steroid users with normal healthy offspring bears testimony to this fact. To further study this issue, the journal Human Reproduction (12:1706-08, 1997) looked at the case histories of four steroid-using athletes.
CASE #1 The first case involved a 31-year-old bodybuilder with a six- year history of infertility due to a low sperm count. This subject had taken eight-week cycles of anabolic steroids for five years. An examination revealed shrunken testicles, a low level of follicle-stimulating hormone (FSH), low levels of luteinizing hormone (LH) and a low testosterone level. He was advised to immediately discontinue steroid use.
Within a year, his sperm count and the motility (movement) of his sperm had both improved. His LH and FSH levels returned to a normal range, although his testosterone level remained slightly below normal. After 11/z years of laying off steroids, his sperm count rebounded to normal, but his testosterone still lagged. Despite this, the subject's wife became pregnant 20 months after he ceased steroid use.
CASE #2 The subject was a 33-year-old man who was diagnosed infertile, with no sperm levels. While both his FSH and LH were below normal, his testosterone levels were in the standard range, likely due to the anabolic steroids he was taking at the time of the examination.
He quit all steroid use and was reevaluated six months later. He still showed below-normal values of FSH and LH, but this time his testosterone level was barely measurable. Two months later, however, his testosterone level rebounded to normal and his sperm concentration improved. Unfortunately, he dropped out of therapy at that point and returned to using steroids.
CASE #3 This case study involved a 27-year-old steroid-abusing athlete with a three-year history of infertility. Like the other steroid users, he quit using the drugs and showed slow but consistent improvement in his sperm count and testicular volume. Twenty-two months after he stopped taking steroids, he and his wife produced a child.
CASE #4 The fourth subject was a 28-year-old bodybuilder who had been infertile for a year. He admitted to having taken steroids for the four years prior to the onset of infertility, and he showed the expected low levels of FSH, LH and testosterone. He discontinued steroid use, however, and was able to impregnate his wife nine months later.
These four infertility cases resulted from the negative feedback of a mechanism of the hypothalamic-pituitary axis in the brain. The steroids may also have had a localized effect directly on the cells in the testes, where testosterone is synthesized.
The primary abnormalities included either a complete lack of sperm or too few sperm to induce a pregnancy. Other problems related to the lack of fertility in these men involved sluggish sperm motility and defects in sperm structure.
Importantly, however, sperm count improved in all these men after they ceased drug use, though the recovery time varied among the individual subjects. Data from research involving the contraceptive usage of steroids shows that it often takes up to a year to return to full fertility. Contraceptive applications involve testosterone doses far smaller than those typically used for athletic enhancement. As such, the time scale for return of full fertility to athletes who use steroids remains speculative and may (as noted in these cases) also depend on individual response.
BECOMING WHOLE AGAIN Other medical research also points to an eventual return of fertility if all steroid usage is stopped. But it's important to remember that even after steroids are discontinued, sperm production still takes time to return to normal values. Once sperm synthesis is curtailed (as with steroid usage), it takes a minimum of 64 days for sperm cells to appear in the seminiferous tubules of the testes. It then takes another one to 20 days for the sperm to travel through the testicular ductal system.
Some researchers believe, however, that if fertility hasn't improved within six months of ceasing steroid usage, some medical intervention is prudent. Such treatment most often involves the administration of gonadotropins in an effort to prod lagging endogenous testosterone and sperm production. Specifically, it involves providing drugs such as intramuscular injections of human chorionic gonadotropin (HCG), which mimics the effects of LH, and possibly human menopausal gonadotropin, which is used to promote pregnancy in women and sperm production in men.
The bottom line? Steroid use doesn't equate to permanent infertility. The longer a man uses steroids, though, the greater his chance of persistent fertility problems, due to possible atrophy of pituitary gonadotroph cells. If these cells don't return to normal volume, the steroid user may be in for a lifetime of testosterone injections to solve his sperm-production problems.