Men may have seen ads asking whether they’ve “lost that loving feeling” and wondered whether they should get their testosterone levels tested. The promises made by pharmaceutical companies pitching testosterone creams or gels directly to men sound too good to pass up: bigger muscles, more energy, stronger sex drive. And prescriptions for the therapy have jumped more than 500 percent over the past two decades.

Whether men should get tested and treated for “low-T” — as drug company ads call it — remains controversial because of unknown risks of long-term testosterone therapy and hints that it could cause life-threatening health problems in older men who tend to have the lowest levels.