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Growth Hormone Suppression after an Oral Glucose Load in Children

Neuroendocrine Unit (M.M., J.C., R.P., K.K.M., A.K.), Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02114; and Pediatric Endocrine Unit (M.M., R.P.), MassGeneral Hospital for Children and Harvard Medical School, Boston, Massachusetts 02114

Address all correspondence and requests for reprints to: Madhusmita Misra, M.D., M.P.H., BUL 457, Neuroendocrine Unit, Massachusetts General Hospital, 55 Fruit Street, Boston, Massachusetts 02114. E-mail: mmisra{at}partners.org.

Background: GH nonsuppression after oral glucose is diagnostic for GH excess, but normative data are lacking in children. Adult data cannot be extrapolated to children given the pubertal increase in GH concentration. In addition, because GH levels are higher in pubertal girls than boys, nadir GH may differ across gender.

Objective: Our objective was to determine whether nadir GH during an oral glucose tolerance test (OGTT) is gender and pubertal stage specific. We hypothesized that nadir GH would be higher in girls, and at the pubertal stage known to correspond with peak height velocity (Tanner 2–3 in girls and Tanner 3–4 in boys) and maximal GH concentrations.

Subjects/ Methods: A 2-h OGTT using 2.35 g/kg oral glucose (maximum 100 g) was performed in 64 girls and 43 boys, 9–17 yr (10th-90th percentiles for body mass index). Girls were grouped as group 1 (Tanner 1), group 2 (Tanner 2–3), and group 3 (Tanner 4–5), and boys as group 1 (Tanner 1–2), group 2 (Tanner 3–4), and group 3 (Tanner 5).

Results: Nadir GH was higher in girls than boys, and in group 2 girls and boys than the other two groups. The upper limit for nadir GH was highest in group 2 girls (1.57 ng/ml), and lower for the other two groups of girls (0.64 ng/ml), and for boys (0.50 ng/ml). All but one girl, and all boys suppressed to less than 1.0 ng/ml. There were 16 girls and five boys who had a nadir GH of more than 0.3 ng/ml.

Conclusion: GH suppression after oral glucose is gender and pubertal stage specific.