"After age 30, most men begin to experience a gradual decline in testosterone," states David Samadi, MD, chairman of the urology department at Lenox Hill Hospital in New York City.
Though testosterone levels never reach zero (as estrogen levels do in women during menopause), low testosterone levels men to experience symptoms such as fatigue, low libido, and loss of muscle mass.
While reduced testosterone is more common in older men, it may occur in younger guys as well. Luckily, all the causes of low testosterone in young guys are treatable, so if you encounter such symptoms at any given age, there's no reason to dismiss it.
Causes of Low Testosterone in Younger Men
For younger men, a drop in testosterone levels may be caused by some illnesses, including type 2 diabetes, chronic liver or kidney disease, COPD or other lung disorder, or pituitary gland issues, according to Dr. Samadi.
Genetic causes of low testosterone in men include the ailments Klinefelter syndrome, Kallmann syndrome, Prader-Willi syndrome, and Myotonic dystrophy. Another disease which can result in low testosterone is hemochromatosis, which makes the body store too much iron.
"Low testosterone can also result when something happens, like trauma or steroid use, that prevents the testes from making the hormone," states Bruce Gilbert, MD, PhD, an adjunct clinical professor of urology and reproductive medicine at Weill Cornell Medical College and director of reproductive and sexual medicine at the Smith Institute for Urology of their North Shore-LIJ Health System.
Other causes of low testosterone in men younger than 50 contain adrenal gland tumors, HIV disease, and radiation treatment or chemotherapy for cancer.
Doctors categorize causes of low testosterone as secondary or primary.
"Primary hypogonadism stems from a problem in the testicles," Samadi says. In secondary hypogonadism, the testicles are normal but function improperly because of a problem with the hypothalamus or pituitary gland."
Can It Be Low Testosterone?
Regardless of the cause, low testosterone symptoms would be the same.
"Symptoms include low libido, erectile dysfunction, fatigue, decreased mental acuity and moodiness," Dr. Gilbert says.
If you suspect low testosterone, the first step is to see your primary care physician.
If your blood test reveals low testosterone (usually defined as a level lower than 300 ng/dL), the doctor may treat you or refer you to a specialist, such as an urologist or endocrinologist.
"When it comes to treating low testosterone in older men, we generally reserve treatment for people who have symptoms, such as fatigue and low libido," Gilbert says.
In men who don't make the hormone in their testes because of a condition such as Klinefelter syndrome, or those who have lost their testes because of cancer, the only option is testosterone replacement therapy.
In these circumstances,"treatments are usually used just in the brief term, and if a physician has close observation and knowledge of the patient," Gilbert says.
An important consideration for younger men before getting treatment is fertility. "You don't wish to give supplemental testosterone to men who want to be fertile because it can turn off sperm production," Gilbert says.
Once a young man goes off testosterone supplementation, there's a chance his sperm count will never return to what it was before he started. "Therefore, men of reproductive age should consider alternatives that might increase their testosterone as well as preserve their sperm production," he says. One such alternative is a category of drugs known as selective estrogen receptor modulators (SERMs).
Other treatments for low testosterone include weight loss and other lifestyle changes, like eating healthier and increasing exercise.
The bottom line, though, is that if you've got low testosterone symptoms, it's important to see your doctor. Then, your doctor can rule out potentially more serious causes of your symptoms, including hypertension or a thyroid problem, and give treatment that could improve your energy and high quality of life.