Background: Oral glucose tolerance test (OGTT) is a step in the evaluation of children and adolescents with tall stature for documenting a possible autonomous GH secretion.
Aim: Assessment of GH dynamics in OGTT in children and adolescents with tall stature in various stages of pubertal development for documenting a possible autonomous GH secretion.
Method: Our study included 44 subjects, 18 girls and 26 boys, with age between 6.5 and 17.3 years diagnosed with constitutional tall stature. The inclusion criterion was height ≥+2 S.D. The exclusion criteria were: diabetes, thyroid dysfunction, Cushings syndrome, hypothalamicpituitary pathology, renal failure, medication that alters glucose/GH dynamics such as estrogen and thyroid hormones. The following parameters were assesed: historical and auxological data, clinical examination, laboratory evaluations: karyotype, thyroid function, androgens, IGF1, IGFBP3, prolactin, evaluation of other pituitary hormone deficiency, age bone, cardiac ultrasound, eye examination, CT/MRI of the hypothalamicpituitary region. OGTT was performed with 1.75 g/kg of glucose po. Glucose and GH (CLIA method) were tested at 0, 30, 60, 90 and 120 min. Statistical analysis was performed using PASW Software version 18, 2010.
Results: GH suppression was different according to sex and pubertal stage. For boys in stage III and IV Tanner we observed GH values >1 ng/ml. For girls GH nadir was higher than for boys. The lowest value of GH both for girls and boys was at 90 min. Two patients with IGF1 >+2 S.D. for chronological age had normal levels of IGFBP3. In six patients with GH suppression >1 ng/ml, the levels of IGF1 and IGFBP3 where normal.
Conclusions: Because GH level is high at puberty compared to the level seen in adulthood data obtained in the oral glucose tolerance test in adulthood can not be extrapolated for children and adolescents. It is necessary to establish new cutoff for GH suppression in oral glucose tolerance test according to sex and pubertal stage both for normal height and tall stature.
27 Apr - 01 May 2013
European Society of Endocrinology