x. Androgens

Although it is still unknown how they do their job, androgens like other hormones form the basic condition for normal sexual function in women. Sufficient testosterone appears to be necessary in both sexes for sexual thoughts and fantasies and for the sensitivity of the brain and genitals to sexual stimuli. But we do not know where the threshold is for ‘androgen deficiency’. 
For the time being, substitution with androgens is indicated only in cases where there is a pattern of symptoms consistent with androgen deficiency and a clear explanation for that deficiency, such as the premature loss of ovarian function due to an operation, radiotherapy or chemotherapy, despite an adequate estrogen hormone level. 
Androgens are also a basic condition for sexual desire in men, but this requires only very low levels of testosterone. Deficiency can become apparent through the absence of morning erections. In such cases, it is useful to check hormone levels. This also includes prolactin. High levels of prolactin can reduce libido and arousal, in men as well as women.
In short, the role that hormones play in human sexual function is conditional rather than causal (i.e. they do not bring about arousal).