Endocrine Abstracts

Introduction: At puberty, the raise of serum estradiol (E₂) (after testosterone conversion) is needed to fuse ephiphyses and to complete bone maturation in boys. Owing to severe hypogonadism and very low circulating testosterone, adult men with congenital hypogonadotropic hypogonadism (CHH) may present with unfused epiphyses and continuing linear growth if androgen deficiency is unrecognized and untreated. In order to establish the minimal amount of sex steroids needed to ensure bone maturation, we prospectively studied 28 caucasian men first diagnosed as CHH in adulthood (a very rare clinical condition) and we compared 11 adult CHH men (mean age±S.D.: 22.7±6.1) with fused epiphyses to 17 adult CHH men (mean age±S.D.: 21.8±4.3) with unfused epiphyses.

Methods: Serum testosterone, E₂, LH, FSH were assayed. Bone age, target height, Tanner stage, anthropometrical measurements (height, arm span, upper (U) and lower (L) segments) and bitesticular volume (b-TV) were calculated.

Results: Bone age, testosterone, E₂, Tanner stage, b-TV were significantly lower in HH men with unfused than with fused epiphyses (P<0.001). Height, arm span, the arm span/height and the U/L ratios, and the difference between patient’s height and his target height were significantly greater in HH men with unfused than with fused epiphyses (P<0.001). All patients with unfused epiphyses had E₂<15 pg/ml and all patients with fused epiphyses had E₂>20 pg/ml, while testosterone resulted partially overlapped in the two groups.

Conclusion: A threshold of 20 pg/ml exists for serum E₂ above which epiphyseal closure and bone maturation may be reached in men. Setting this threshold is challenging for targeting some kind of treatment for short or tall stature in boys, like aromatase inhibitors or androgens respectively. Unfused epiphyses, tall stature and eunuchoid skeleton all depend from circulating estrogens rather than androgens not only in genetic diseases due to congenital estrogen deficiency.