Hypogonadism (decreased production of testicular or ovarian hormones resulting in incomplete sexual development) is considered to be a cardinal feature of Prader-Willi syndrome, however, the clinical expression is variable. Most, but not all PWS males have unilateral or bilateral undescended testes. Arrested pubertal development leads to inadequate virilization in PWS men. While some PWS women experience spontaneous onset of menstrual periods, nearly all develop secondary amenorrhea. Consequences of inadequate production of sex hormones include immature body appearance, decreased muscle strength, and osteoporosis. Nevertheless, some PWS children experience onset of puberty at an abnormally early age and rare cases of pregnancy in PWS women have been described.
Although the cause of hypogonadism in PWS was generally attributed to hypothalamic dysfunction, we have recently shown that a specific gonadal (testes and ovaries) defect plays a major role in contributing to the inadequate sex hormone production in this syndrome. There are no studies, however, which describe the natural development of sexual hormones in a large group of PWS individuals over several years. In view of the unpredictable variability in clinical expression of hypogonadism, these data are needed in order to develop clear guidelines regarding sex hormone replacement in PWS.
We plan to study over 90 patients with PWS who are followed in our national, multidisciplinary PWS clinic. We will obtain blood samples for pituitary and gonadal hormones including LH, FSH, testosterone, and estradiol. In addition, we will measure levels of newer, specific indicators of gonadal function, inhibin B and anti-Mullerian hormone. Hormone levels will be compared with levels obtained from the same patients one to two years earlier, which were taken as part of our initial cross-sectional study.
These results will increase our understanding of the natural history of sexual hormone and pubertal development in PWS and help to determine which patients and at what age hormonal replacement therapy should be given. Evidence of primary gonadal vs hypothalamic causes of hypogonadism may be relevant the type of hormonal replacement should be offered based on the individual patient’s hormonal profile. These findings may identify those PWS women who are potentially fertile in order to recommend contraceptive measures.
Learn more about the importance of growth hormone therapy for PWS.
Research Outcomes: Project Summary
Initial results of our longitudinal study of pubertal and reproductive hormones demonstrate several distinct patterns of hypogonadism in PWS. The predominant pattern in our study reflects a primary gonadal defect characterized by elevated FSH levels and undetectable serum levels of inhibin B. Hypothalamic hypogonadism with low FSH and low inhibin B was less common. Other study participants had hormonal patterns suggesting partial defects in hypothalamic and gondal function. Serial blood samples indicate that classification of the type of hypogonadism is possible beginning in late adolescence and that specific hormone patterns remain consistent for each individual patient. Recognition of differences in hypogonadal phenotypes may be important for development of guidelines for individualized hormone replacement therapy. Furthermore, characterization of hormone patterns including inhibin B levels, may indicate potential fertility in some PWS women.
Research Outcomes: Publications
Sexual dichotomy of gonadal function in Prader-Willi syndrome from early infancy through the fourth decade. Hirsch HJ, Eldar-Geva T, Bennaroch F, Pollak Y, Gross-Tsur V. Human Reproduction. 2015 Nov;30(11):2587-96.
Characterization of minipuberty in infants with Prader-Willi syndrome. Hirsch HJ, Eldar-Geva T, Erlichman M, Pollak Y, Gross-Tsur V. Hormone Research in Paediatrics. 2014;82(4):230-7.Body image and sexual interests in adolescents and young adults with Prader-Willi syndrome. Varda Gross-Tsur, Talia Eldar-Geva, Fortu Benarroch, Orit Rubinstein, and Harry J Hirsch. Journal of Pediatric Endocrinology and Metabolism. 2011; 24(7-8): 469-475.
Harry Hirsch, MD
Shaare Zedek Medical Center, Israel