Low testosterone does not announce itself with one clear sign. Two health sources list the symptoms, and they overlap enough to give a Midtown reader a working checklist.
The symptoms most often listed
MedlinePlus lists these possible symptoms of low testosterone: low sex drive, erectile dysfunction (difficulty getting or keeping an erection), infertility (difficulty getting someone pregnant), enlarged breasts, lack of face or body hair, thinning bones or anemia without a known cause, and loss of muscle mass.
Read the list as a set and write down every item that fits you.
Changes that build over time
The Endocrine Society says that over time, low testosterone may cause a man to lose body hair and muscle bulk, and may cause weak bones (osteoporosis), low red blood cells and smaller testes.
These are slower changes. Notice the direction of travel and the dates, because a clinician will ask when each one began. The society's hypogonadism in men page is a good place to read more about them.
Where the two lists agree
Both sources name loss of body or face hair and loss of muscle. Both also name bone problems, with the Endocrine Society using the word osteoporosis. Repeated items are the ones to put at the top of your list.
When symptoms point to testing
Symptoms alone do not confirm a low level. The Endocrine Society's statement on testosterone replacement therapy is a plain place to start reading about how clinicians approach treatment. A narrative review of testosterone replacement therapy in men aged 50 and above goes further into benefits, safety considerations and clinical recommendations.
Your symptom list
Write down each symptom, the date you first noticed it, and whether it is getting worse. Take that list to a clinician and ask what testing would clarify it.