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- How to define reversible congenital isolated hypogonadotropic hypogonadism?
Reversible congenital isolated hypogonadotropic hypogonadism in a male is
defined as sustained maintenance of serum testosterone levels in the normal
adult range (>9 nmol/L), irrespective of testicular volume after discontinuation
of hormonal therapy including GnRH, gonadotropins, or androgens. The crite-
ria to define reversibility in females with IHH are not clear.- What is the mechanism of reversibility in hypogonadotropic hypogonadism?
The mechanism of reversibility in patients with isolated hypogonadotropic
hypogonadism remains elusive; however, various theories have been proposed
to explain this phenomenon. The reversal may be due to the presence of muta-
tions which results in delayed maturation of GnRH neurons (rather than muta-
tion which prevent the development of these neurons). Plasticity of GnRH
neurons (ability of neurons to adapt to the environment) has also been proposed
to explain the reversibility of IHH. The plasticity of GnRH neurons may be
amplified by therapy with gonadal steroids.abcFig. 7.11 Coronal T2W MRI brain showing: (a) normal olfactory bulb (white arrow) and sulci
(red arrow) in a patient of normosmic IHH, (b) hypoplastic olfactory bulb (red arrows) and absent
sulci in a patient with anosmia due to Kallmann syndrome
7 Delayed Puberty