How Does Testosterone Replacement Therapy Affect Fertility?

May 26, 2015

As a urologist actively involved in screening and treating men with low testosterone, I’m frequently asked about the possible dangers posed to sperm production and overall fertility by testosterone-replacement therapy (TRT). This is a serious concern regardless of whether a man is supplementing his testosterone with topical medicine or injections.

A major recent study conducted by the University of Southern California Institute of Urology addressed this very question, reviewing some 4,400 men who sought evaluation of their fertility. Only 59 of these men (barely more than 1 percent) were taking testosterone, and 52 of them (88.1 percent) produced no sperm whatsoever in a semen analysis.

Astonishing, isn’t it? Nearly nine of every 10 men taking testosterone produced absolutely no sperm, and would therefore be unable to father a child. The researchers then tracked these men after they ceased TRT, and happily, nearly two-thirds of them recovered their normal sperm count within six months. That’s good news for them — but it still means that about 35 percent of the men didn’t.

Caveats abound: The researchers didn’t report whether they followed these men for longer than six months to see if their sperm counts ever recovered; it’s also unclear if those men had been treated with TRT for a longer time before these tests established their infertility.

Patients understandably dislike medical uncertainty of any kind, but the truth is, we’re unable to know whether most men will ultimately resume normal sperm production after stopping traditional TRT. Do a patient’s age and the time he’s spent being treated offer any clues, and if they do, how long should a man wait before seeking conventional fertility treatments?

We just don’t know yet. But the USC study illustrates an important fact: We’re likely to see more men with fertility concerns if they’re currently using TRT or have done so recently. If you’re considering testosterone-replacement therapy yet want to maintain your fertility, discuss your concerns with your doctor ahead of time. The future of the human race — well, your little corner of it, anyway — depends on it.