What risks do you consider when prescribing testosterone-replacement therapy?
When patients ask about risks, I remind them that they already have testosterone in their system and that the goal of testosterone treatment is to restore its concentration back to what it was 10 or 15 years previously. And the molecule itself that we give is identical to the one that their bodies make naturally, so in theory, everything should be hunky-dory. But in practice, there are always some curveballs.
For example, testosterone can increase the hematocrit, the percentage of red blood cells in the bloodstream. If the hematocrit goes up too high, we worry about the blood becoming too viscous or thick, possibly predisposing someone to stroke or clotting events.
Although, frankly, in a review that I wrote in the New England Journal of Medicine* where we reviewed as much of this as we could, we found no cases of stroke or severe clotting related to testosterone therapy. Nevertheless, the risk exists, so we want to be careful about giving testosterone to men who already have a high hematocrit, such as those with chronic obstructive pulmonary disease, or those who have a red-blood-cell disorder.
Although it’s rare to see swelling caused by fluid retention, physicians need to be careful when prescribing testosterone to men with compromised kidney or liver function, or some degree of congestive heart failure. It can also increase the oiliness of the skin, so that some men get acne or pimples, but that’s quite uncommon, as are sleep apnea and gynecomastia (breast enlargement).