Background: Hypogonadism is one of the major diagnostic criteria of Prader-Willi syndrome (PWS). A hypogonadotropic hypogonadism is often present as a result of hypothalamic dysfunction (together with other hormonal disorders, such as growth hormone deficiency and hypothyroidism).
Presentation: A 8.5-year-old boy with genetically-confirmed PWS (maternal uniparental disomy) presented in our Endocrinology Unit for routinely follow-up. Therapy with rhGH was started at 1.5 years without provocative diagnostic testing, with good response on growth and motor performance. Therapy with L-thyroxine was started at 2 years because of central hypothyroidism. At 3 years, congenital cryptorchidism was surgically corrected with bilateral orchidopexia, which resulted in asymmetric testis (hypotrophy of the left one). A physical examination revealed precocious pubertal development: volume of the right testis 5 ml, Tanner stage II for pubic hair and genitalia. BMI was in normal range. Growth rate was accelerated (9.4 cm/year, +4.83 SDS) with advanced bone age (10 years according to the Greulich and Pyle method). A GnRH test revealed premature activation of the hypothalamic-pituitary-gonadal axis (peak value LH 11.6 mUI/ml, FSH 10.8 mUI/ml) with pubertal testosterone levels (1.15 ng/ml). Serum IGF-1 level and thyroid function test were normal. A brain MRI showed mild hydrocephalus (as a result of neonatal intraventricular haemorrhage) and a normal pituitary gland. Gonadal ultrasound demonstrated testicular microlithiasis. Tumour markers (hCG, aFP) were negative. With a final diagnosis of central precocious puberty (CPP), LHRH analogue therapy was started, obtaining good clinical and hormonal response.
Conclusion: Fourteen cases of CPP in PWS have been reported so far. The aetiology remains largely unknown (except for few cases with pituitary anomalies or brain ischemic damage). Our patient presented CPP with only one functioning microlithiasic testis. We hypothesize that perinatal brain damage could have contributed to premature activation of the axis.
10 Sep 2016 - 12 Sep 2016