[3][6] In their late 40s and early 50s, some men may experience depression, loss of libido, erectile dysfunction, and other physical and emotional symptoms.

These symptoms include irritability, loss of muscle mass and reduced ability to exercise, weight gain, lack of energy, difficulty sleeping, and poor concentration.

[3] If a person has symptoms of late-onset hypogonadism, testosterone is measured by taking blood in the morning on at least two days; while immunoassays are commonly used, mass spectrometry is more accurate and is becoming more widely available.

Increased concentrations of proteins that bind testosterone in blood occur if the person is older, has hyperthyroidism or liver disease, or is taking anticonvulsant drugs (which are increasingly used for depression and various neuropathies), and decreased concentrations of proteins that bind testosterone occur if the person is obese, has diabetes, has hypothyroidism, has liver disease, or is taking glucocorticoids or androgens, or progestins.

[3] Other significant adverse effects of testosterone supplementation include acceleration of pre-existing prostate cancer growth; increased hematocrit, which can require venipuncture to treat; and, exacerbation of sleep apnea.

In 1944, Heller and Myers identified symptoms of what they labeled the "male climacteric" including loss of libido and potency, nervousness, depression, impaired memory, the inability to concentrate, fatigue, insomnia, hot flushes, and sweating.

[15][16] The 1997 book Male Menopause[17][18] by Jed Diamond, a psychologist with a PhD in international health,[19] fueled popular interest in the concept of "andropause".

[citation needed] Diamond regards andropause as a change of life in middle-aged men which has hormonal, physical, psychological, interpersonal, social, sexual, and spiritual aspects.

[22][23] Thomas Perls and David J. Handelsman, in a 2015 editorial in the Journal of the American Geriatrics Society, say that between the ill-defined nature of the diagnosis and the pressure and advertising from drug companies selling testosterone and human-growth hormone, as well as dietary supplement companies selling all kinds of "boosters" for aging men, the condition is overdiagnosed and overtreated.