Hypogonadism in the Prader-Willi syndrome from birth to adulthood: a 28-year experience in a single centre.

Background: Hypogonadism is a key feature of Prader-Willi syndrome (PWS) but clear strategies for hormone replacement are lacking.

Objective: To evaluate gonadal status and outcome in patients attending a Scottish PWS clinic from 1991-2019.

Methods: In 93 (35F:56M) patients, median follow-up 11.2 years, gonadal and pubertal status were assessed clinically. Pelvic ultrasound findings and basal/stimulated gonadotrophins were compared with age-matched controls.

Results: Females: Of 22 patients aged >11, 9 had reached B4-5, while 5 were still at B2-3, and 6 remained prepubertal. Eight patients experienced menarche aged 9.8-21.4 years, none with a normal cycle. Uterine length and ovarian volumes were normal but uterine configuration remained immature, with low follicular counts. Gonadotrophins were unremarkable, serum estradiol 129 (70 - 520) pmol/L. Only 5 patients received oestrogen replacement. Males: Fifty-four (96%) patients were cryptorchid (9 unilateral). Weekly hCG injections resulted in unilateral/bilateral descent in 2/1 of 25 patients. Of 37 boys aged >11, 14 (9 with failed/untreated bilateral cryptorchidism) failed to progress beyond G1, 15 arrested at G2-3 (testes 3-10 ml), and 8 reached G4-5. Gonadotrophins were unremarkable except in boys at G2-5 in whom FSH was elevated: 12.3/27.3 vs 3.25/6.26 U/L in controls (p<0.001). In males aged >13, testosterone was 3.1 (0.5-8.4) nmol/L. Androgen therapy, given from 13.5-29.2 years, was stopped in 4/24 patients owing to behavioural problems.

Conclusion: Despite invariable hypogonadism, few females and only half the males with PWS in this study received hormone replacement. Double-blind placebo-controlled crossover trials of sex steroids are required to address unproven behavioural concerns.