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- What is the utility of FSH in the induction of puberty in boys with congenital
IHH?
The aim of therapy in a patient with congenital IHH is not only to induce viril-
ization but also to initiate and maintain spermatogenesis. Although the most
common agent used to induce virilization is testosterone, it does not initiate
spermatogenesis. Therapy with hCG induces virilization in majority of patients
with congenital IHH and can initiate spermatogenesis in 20–30 % of patients,
who have residual endogenous FSH activity. However, patients with complete
deficiency of gonadotropins (both FSH and LH) as evidenced by small testes
(testicular volume <4 ml) should be treated with hCG along with FSH, either
sequentially or simultaneously, to increase testicular size and initiate spermato-
genesis. The recommended dose of FSH is 75–300 IU administered subcutane-
ously or intramuscularly two to three times a week. However, it should be
remembered that isolated FSH therapy does not result in virilization or
spermatogenesis. - When to initiate combined gonadotropin therapy in boys with congenital IHH?
Both LH and FSH act in concert to induce spermatogenesis; FSH induces the
expression of LH receptor on Leydig cells and LH provides a support for germ
cells by increasing the intratesticular testosterone. However, it is not clear
whether to initiate combined gonadotropin therapy, at induction of puberty or
when fertility is desired. The data regarding combined therapy with gonadotro-
pins are scarce. It has been shown that early use of combined therapy (at
15–20 years) is more effective for initiation of spermatogenesis, as compared to
its use in older subjects (at 25–30 years). Therefore, early use of combination
therapy with hCG and FSH may be useful, especially in boys with testicular
volume of <4 ml, during mid-late adolescence for optimal pubertal develop-
ment including spermatogenesis.- What are the predictors of response to gonadotropin therapy in a male with
congenital IHH?
The predictors of response to gonadotropin therapy in a patient with congenital
IHH include testicular volume (>4 ml), absence of cryptorchidism and micro-
penis, higher serum inhibin-B level (>35 pg/ml) at presentation, and early ini-
tiation of gonadotropin therapy. Few patients (10 %) with underlying genetic
mutations associated with reversible IHH may also respond better (Fig. 7.14).
7 Delayed Puberty