GnRH infusion recommended for adolescent hypogonadotropic hypogonadodism

By Eleanor McDermid, Senior medwireNews Reporter

Pulsatile gonadotropin-releasing hormone (GnRH) may be more effective than human chorionic gonadotropin (hCG) for the treatment of peripubescent boys with hypogonadotropic hypogonadodism (HH), say Chinese researchers.

The two treatments reportedly have equivalent efficacy in adult HH patients, but Chunxiu Gong (Capital Medical University Affiliated Beijing Children Hospital, China) and co-workers found that, in adolescent boys, pulsatile GnRH resulted in larger increases in testicular size and sex hormone levels than hCG did.

“However, the choice of treatments must be balanced by the cost and the patient’s desire”, they write in The Journal of Clinical Endocrinology & Metabolism.

They observe that pulsatile pump GnRH treatment is expensive, available only through hospitals and can affect patients’ life quality, so hCG is more often used due to its lower cost and ease of use.

The trial was not randomised; 12 of the 34 patients chose GnRH treatment and 22 opted for hCG, citing the expense and inconvenience of GnRH. Patients in the GnRH group received a dose of 8–10 µg every 90 minutes, while those taking hCG received it as a 1000 IU intramuscular injection twice weekly for 3 months, then every other day for 3 months, after which the pattern was repeated with a dose of 2000 IU.

Testicular volume was similar in the two groups at baseline, at an average of 2.53 mL in the GnRH group and 2.15 mL in the hCG group. It increased in both groups during treatment, but after 12 months it was significantly greater in the GnRH than hCG group, at 13.09 versus 6.01 mL.

Penile length and testosterone levels increased during treatment, with no significant differences between the groups. But levels of luteinizing hormone and follicle stimulating hormone increased only in patients treated with GnRH, and these differences were seen after just 3 months of treatment.

The better results in the pulsatile GnRH group occurred irrespective of whether the patients had Kallmann’s syndrome or normosmic idiopathic HH.

The researchers note that hCG acts directly on Leydig cells, whereas GnRH is produced by the hypothalamus and acts on the pituitary. “The problem in HH patients is located in the hypothalamus, therefore it is the best to treat at the hypothalamic level”, they say.

One patient treated with GnRH and one who had received hCG followed by GnRH reported nocturnal emission.

“Based on the increase in testicular volume and the levels of testosterone after GnRH treatment, we expect more patients to have successful spermatogenesis when they reach puberty”, says the team. “Whether continued treatment is necessary to maintain spermatogenesis warrants further study.”

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