The following is a summary of “Testicular Dysfunction in 47,XXY Boys: When It All Begins. A Semilongitudinal Study,” published in the October 2023 issue of Endocrinology by Pozza, et al.

Klinefelter syndrome is the most prevalent chromosomal disorder in males and a leading cause of hypergonadotropic hypogonadism. For a study, researchers sought to elucidate the natural progression of testicular dysfunction in individuals with Klinefelter syndrome by integrating clinical, hormonal, and quantitative ultrasound data across their life course.

The study encompasses 155 participants with a 47,XXY karyotype, aged between 7 months and 55 years, who have not undergone testosterone replacement therapy. Subjects were categorized based on their pubertal stage and age group, including transition age and adulthood. Serial assessments were conducted to collect clinical, hormonal, and testicular ultrasound (US) data.

Testicular development advances until reaching Tanner stage 4, after which regression occurs. Sertoli and germ cell dysfunction are not hormonally detectable until Tanner stages 3-4, evidenced by the persistence of normal inhibin B levels until stage 4, followed by a decline in the inhibin B/follicle-stimulating hormone ratio. The testosterone/luteinizing hormone ratio peaks during Tanner stages 2-3, gradually decreasing from Tanner stage 4 onwards, foreshadowing the onset of hypogonadism. Testicular ultrasound echotexture progressively deteriorates until the transition age, indicating ongoing gonadal compromise. Furthermore, quantitative ultrasound echotexture measurements, hypoechoic lesions, and microlithiasis independently and significantly predict lower circulating testosterone levels.

The extensive prospective study enhanced the comprehension of the natural course of testicular dysfunction in Klinefelter syndrome, emphasizing the importance of utilizing quantitative testicular ultrasound during infancy, childhood, puberty, and the transition to adulthood to optimize the care of individuals with Klinefelter syndrome.

Source: academic.oup.com/jcem/article/108/10/2486/7116194