Testosterone levels are well-documented to decline with aging at about 1% per year in both men and women after a certain age; the causes are not well understood.
Late-onset hypogonadism
Prepubertal hypertrichosis
Delayed puberty
Hypogonadotropic hypogonadism
Hypergonadotropic hypogonadism
Hypertelorism
Prognathism
Precocious puberty