THE SOMATOTROPIN-SOMATOMEDIN AXIS IN ADULT PATIENTS WITH TURNER SYNDROME - MEASUREMENT OF STIMULATED GH, GH-BP, IGF-I, IGF-II AND IGFBP-3 IN 25 PATIENTS

So far, few studies have addressed the regulation of GH and GH-depende nt growth factors in adult patients with Turner syndrome. We therefore studied a group of 25 genetically proven patients with Turner syndrom e (age 20-50 years) and 10 control women (25-48 years). Turner patient s were significantly shorter (148.7 +/- 1.1 cm vs. 169.1 +/- 2.3 cm; m ean +/- SE; p < 0.0001) and more overweight [body mass index (BMI)] 25 .6 +/- 1.3 vs. 21.4 +/- 0.6 in controls; p < 0.01). No significant dif ferences were present when the integrated GH response to stimulation w ith arginine and the serum levels of GH-binding protein (GH-BP), IGF-I , IGF-II and binding protein 3 for IGFs (IGFBP-3) were compared betwee n the two groups. However, more detailed analysis revealed significant abnormalities of the somatotropic axis in Turner patients. Pituitary GH secretion was negatively and serum GH-BP positively related to the degree of overweight in normal patients. In Turner patients, no such r elationship was present, while IGF-II significantly increased with BMI . IGFBP-3 was positively related to adult height in normal women but n ot in Turner patients. While serum testosterone values did not affect any of the somatotropic parameters measured, there was a previously un reported, inverse relation between serum estradiol and GH-BP in contro ls but not in Turner patients. While adult patients with Turner syndro me do not display endocrine features of GH insufficiency, a detailed a nalysis reveals several abnormalities of the interrelation between ant hropometric parameters, sex steroids and the pituitary-somatomedin axi s.