Assessment of Testicular Function
An intact, functioning hypothalamic-pituitary-gonadal axis is also
required for normal spermatogenesis and reproduction. FSH and LH support
testicular Sertoli cell and Leydig cell function, respectively, and are
responsible for testicular reproductive and androgenic function. Cancer
treatment has been shown to potentially affect both aspects of
testicular function in a dose-dependent and treatment-dependent
manner.(67,75–77) Leydig cells (testosterone-producing cells) are
generally more tolerant of chemotherapy and radiation, and androgen
deficiency is much less common than impaired spermatogenesis in cancer
survivors. As such, a normal testosterone level should not be
interpreted as indicative of normal fertility. After high dose cranial
radiation, high dose alkylating chemotherapy, or high dose testicular
radiation, androgen deficiency can occur with specific symptomatology
including loss of libido and with long-term health consequences, and
will also negatively impact spermatogenesis.(30) Unfortunately,
treatment of androgen deficiency with exogenous testosterone will impair
spermatogenesis, and thus is not an appropriate treatment for men
seeking fertility. Patients with hypogonadotropic hypogonadism following
cranial radiation may have restored ability to sire children after
treatment with gonadotropins.(78) It is for these reasons that early
referral to urology or endocrinology is warranted.