The goal of this clinical trial is to learn if Triptorelin test works to early diagnose hypogonadotrophic hypogonadism in adolescents. The main questions it aims to answer are:

• Does gonadotropin and gonadal steroids responses to Triptorelin test be useful to diagnose early hypogonadotrophic hypogonadism? Researchers will compare gonadotrophins and gonadal steroids in response to Triptorelin subucutaneos test with clasiccal GnRH infusion to diagnose hypogonadotrophic hypogonadism.

Participants will performed two test:

• Triptorelin test (subcutanous)
• LHRH infusion test

Inclusion Criteria:

• Female patients presenting with Tanner breast stage 1 or 2 at age ≥ 13 years or male patients with testicular volume < 5 cc at age ≥ 13.5 years, or who have had pubertal changes but have arrested pubertal development for a period of one year. Female patients presenting with primary amenorrhea (absence of menarche at age 15) > 4 years after the onset of puberty or secondary amenorrhea > 6 months with no other apparent cause (having ruled out other hormonal disorders such as premature ovarian failure, hypothyroidism, hyperprolactinemia, non-classical congenital adrenal hyperplasia, and polycystic ovary syndrome) may also be included. Patients with or without olfactory disorders, and with or without a previous diagnosis of other pituitary deficiencies will be included. In the case of a history of CNS tumor pathology, inclusion in this study will be considered only if the patient is in remission from the oncological disease and if they have received CNS radiotherapy, at least one year has passed since the beginning of the treatment.

If patients have started HRT, they may be included as long as they stop taking it for two half-lives of the compound used, therefore a 2-month free period is necessary for oral tablets or patches and 3 months for monthly testosterone injections or 7 months for testosterone undecanoate injections.

Exclusion Criteria:

• Patients will be excluded if, due to previous history or relevant clinical history or initial laboratory study, another cause is determined to explain their pubertal disorder: primary hypogonadism (hypergonadotrophic or premature ovarian failure), low weight with BMI < 18, untreated hypothyroidism, hyperprolactinemia, hyperandrogenism, Cushing's syndrome, current prolonged corticosteroid treatment, active systemic disease, CRF or competitive training > 10 hours/week, diabetes mellitus without adequate control or celiac disease without compliance with a gluten-free diet.

Patients who do not provide an updated medical history, who do not provide consent, or whose parents or guardians do not provide assent will be excluded. Patients who are receiving hormone replacement therapy and refuse to stop during the 2-month period for oral tablets or patches and 3 months for monthly testosterone injections or 7 months for quarterly depot injections of testosterone undecanoate will be excluded.