Table 1. Summary of known evidence regarding testosterone deficiency.

Known evidence in testosterone deficiency	Levels of evidence
TD confers negative impact on health and quality of life [17–22]	1a
Testosterone therapy can mitigate untoward effects of TD [17–22]	1a
Higher endogenous serum androgen concentrations are not associated with increased risk of developing prostate cancer, or severity of prostate cancer [32,33]	1a
Testosterone therapy is not associated with increased risk or severity of prostate cancer [34–40]	2a
Impact of androgen on prostate cells is subject to a saturation effect [7,9,10,26–28]	2b

TD = testosterone deficiency.