Abstract 33

A disorder of the HPG axis has been described in adults with HI, but no information is available in PM. The aim of this study was to evaluate in 20 PPM with a mean ± SD chronological age (CA) of 5.8 ± 5.50 ys. the following parameters 1 basal levels of serum LH and FSH. 2 changes in serum SHBG, total (t), free (f) and non-SHBG-bound (bioavailable, [B] serum, testosterone (T) and estradiol (E2), and 3 the steroidogenic capacity of the prepubertal testis after hCG stimulation (2500-5000 IU) and the biological response to androgens (BRA) after T administration (2 mg/kg), using as parameters changes in serum SHBG and IGF-1 Serum LH and FSH, SHBG and IGF-1 T and E2 were determined by MEIA, saturation analysis and RIA respectively, while serum fractions of T and E2 were calculated from the law of mass action Serum LH (0.43 ± 0.3 U/L) but not serum FSH (4.53 ± 5.72 U/L) was significatively higher in patients below 1 y of age than in respective controls (C), n=18 (LH:0.21 ± 0.18 and FSH: 5.39 ± 3.38), but similar to C, n=75, in patients with higher CA (LH:0.32 ± 0.22 and FSH:1.03 ± 0.63) In contrast to a previous study in normal subjects (Belgorosky et al. J Clin Endocrinol Metab. 1987) no age related changes in serum SHBG, tT, BT, fT, tE2 and BE2 was observed Serum T after hCG increased above 1 ng/ml in all 10 patients studied (before: 0.15 ± 0.19, after 3.55 ± 1.70, p<0.0001). BRA was positive in only 3/11 (Fisher's test: p=0.001) and no increment in serum IGF-1 was detected (before: 4.81 ± 0.01, after: 13.7 ± 24.8 ng/ml). It is concluded that PPM with HI before Tx have normal testicular steroidogenic capacity. The increased serum LH of infants is suggestive of a disturbance of the negative feedback of the HPG axis. Lack of increment of serum IGF-1 after exogenous T and of the normal decrease of serum SHBG with age suggest partial and GH insensitivity or a local effect secondary to HI.