Eunuchoid skeletal proportions in male hypogonadism: a comparative analysis of anthropometric measures between men with congenital hypogonadotropic hypogonadism (CHH) and Klinefelter Syndrome (KS)

Abstract Disclosure: S. De Vincentis: None. A. Bellelli: None. R. Corleto: None. L. Zirilli: None. A. Granata: None. V. Rochira: None. BACKGROUND: Patients with congenital hypogonatropic hypogonadism (CHH) and Klinefelter syndrome (KS) have eunuchoid body proportions of the skeleton compared to normal male subjects, characterized by tall stature, and reduced upper-to-lower segment ratio (U/L). Vice versa, steroids exposure deeply differs between CHH and KS at puberty, with both testosterone and estradiol being very low only in CHH compared to KS. At present, a comparison of body skeletal proportions between CHH and KS is not available.AIM: To compare anthropometric measurements of adult male CHH patients to adult KS patients.METHODS: A prospective, cross-sectional, observational study was carried out. CHH patients were subdivided into 2 subgroups according to the timing of treatment start (testosterone replacement therapy [TRT] or gonadotropins): CHH1) CHH patients who started treatment late after 18 years; CHH2) CHH patients who started treatment on time before 18. All KS patients did not start TRT before 18 since KS do not usually delay puberty. The following anthropometric measurements were collected by using a digital scale and stadiometer (Seca gmbh&co®): height, weight, sitting height,total arm span. Legs length was obtained by subtracting sitting height from stature; U/L was calculated dividing sitting height for legs length.RESULTS: A total of 70 CHH and 45 KS age-matched patients were enrolled (mean age 33.7±13.7 and 35.3±13.7 years, respectively). CHH1 showed a longer arm span compared to CHH2 (p=0.001) and KS (p=0.003), and a shorter sitting height compared to KS (p=0.008). On the contrary, legslength was shorter in CHH2 compared to CHH1 (p<0.001) and KS (p=0.011). Accordingly, U/L and upper-to-height ratios were lower in CHH1 compared to CHH2 (p<0.001) and KS (p=0.001). Furthermore, the arm span-to-height ratio was higher in CHH1 compared to CHH2 (p<0.001) and KS (p=0.008).CONCLUSIONS: Under the same definition of eunuchoid body proportions, the traditional hallmark of male hypogonadism, more fine differences are observed comparing adult CHH to KS patients. CHH patients who delayed treatment showed longer arms length and lower U/L in comparison to CHH patients receiving treatment on time at pubertal age and KS. This suggests adifferent mechanism involved in the eunuchoid skeleton development between CHH and KS confirming a major role for estrogen/androgen deficiency in the former (leading to disproportional growth of both legs and arms due to delay in epiphyseal closure that could benefit from on timereplacement treatment) and a possible role of genetic supernumerary X in the latter, displaying a disproportional growth only at the legs site since infancy. Presentation: Thursday, June 15, 2023