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Growth deficiency with high circulating growth hormone levels: the insulin stimulation test in 39 children
L Simionescu1, V Dimitriu, D Zamfir-Grigorescu
1C. I. Parhon Institute of Endocrinology, Bucharest, Romania.
Insights
Children with growth deficiency and high human growth hormone (hGH) levels were studied using insulin stimulation tests (IST). Some patients showed paradoxical responses, suggesting complex growth mechanisms.
Area of Science:
- Pediatric Endocrinology
- Growth Hormone Physiology
Background:
- Growth deficiency in children can present with elevated basal human growth hormone (hGH) levels.
- Understanding hGH dynamics is crucial for diagnosing and managing growth disorders.
Purpose of the Study:
- To analyze growth deficiency in children with high basal hGH levels using insulin stimulation tests (IST).
- To investigate the relationship between hGH response, hypoglycemia, and growth parameters.
Main Methods:
- Retrospective analysis of 1,500 insulin stimulation tests (IST) in children and adolescents with growth deficiency.
- Categorization of patients into hGH responders and non-responders based on IST results.
- Evaluation of basal and stimulated hGH levels, hypoglycemia, height, weight, and bone age.
Main Results:
- Thirty-nine patients with abnormal high basal hGH were identified.
- Non-responders exhibited deeper hypoglycemia post-insulin than responders.
- Two siblings displayed extremely high hGH levels, resembling familial Laron type dwarfism.
Conclusions:
- High basal and variable hGH levels in children with growth deficiency suggest complex underlying mechanisms.
- Further research into these mechanisms is needed to guide therapeutic strategies for linear growth.
- The study highlights the heterogeneity in hGH response and its implications for growth disorders.
Abstract:
Thirty nine patients with abnormal high basal hGH levels were selected and analysed as a part of a retrospective study of the results of 1,500 insulin stimulation tests (IST), applied in children and adolescents with growth deficiency. Their height, weight, and bone age were lower than their corresponding chronological age. Both in girls and in boys groups, responders and nonresponders subgroups were detected as judging by the results of the secretagogue action of insulin on hGH. The hGH basal levels were 43.88 +/- 18.27 microU/ml (X +/- SD) in boys (no = 22) and 56.61 +/- 35.21 microU/ml in girls (no = 17). It is to be noted that the hGH nonresponder group had deeper hypoglycemia at 30 minutes post-insulin injection than the responder group: 53.6 +/- 13.0 mg/100 ml (X +/- SD) vs 66.0 +/- 11.5 mg/100 ml respectively (p less than 0.01). Two siblings, a girl and a boy, had the highest basal and stimulated hGH, either during the IST or starvation. One of them, the boy, during the starvation test, had a paradoxical fall of about two orders of magnitude of the serum hGH 4 hr after basal sample collection. These two siblings are similar to the familial Laron type dwarfism. The possible mechanisms of growth deficiency in children with constant high but variable hGH values are discussed, as well as the aspects concerning the therapeutic ways to improve their linear growth.