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[Insulin, glucagon and growth hormone responses during glucose, arginine and insulin tolerance tests in children with
Insights
Hyperthyroid children exhibit glucose intolerance with elevated blood glucose levels after oral glucose load, despite normal insulin response. This suggests underlying peripheral insulin resistance in pediatric hyperthyroidism.
Area of Science:
- Pediatric Endocrinology
- Metabolic Disorders
- Thyroid Disorders
Background:
- Glucose intolerance is common in adult hyperthyroidism.
- Reports of glucose intolerance in hyperthyroid children are limited.
- Understanding metabolic changes in pediatric hyperthyroidism is crucial.
Purpose of the Study:
- To investigate glucose metabolism and hormonal responses in hyperthyroid children.
- To compare metabolic profiles of hyperthyroid children with healthy controls.
- To identify potential insulin resistance in pediatric hyperthyroidism.
Main Methods:
- Oral glucose tolerance test (OGTT) in hyperthyroid children and controls.
- Arginine and insulin tolerance tests were also performed.
- Plasma glucose, insulin, glucagon, and growth hormone levels were measured.
Main Results:
- Hyperthyroid children showed significantly higher peak glucose levels during OGTT.
- Insulin levels were elevated in hyperthyroid children, with age-related differences in timing.
- Insulinogenic index decreased in pubertal hyperthyroid children, and glucagon levels were lower.
Conclusions:
- Hyperthyroid children demonstrate impaired glucose tolerance.
- Peripheral insulin resistance is suggested by elevated glucose with normal insulin-glucose ratios.
- Further research is needed to elucidate the long-term metabolic implications.
Abstract:
There are many reports of glucose intolerance in adult patients with hyperthyroidism but few reports of glucose intolerance in hyperthyroid children. In this study, we measured plasma levels of glucose, insulin, glucagon and growth hormone in hyperthyroid children and control subjects by the use of three kinds of tolerance tests: an oral glucose tolerance test, an arginine tolerance test and an insulin tolerance test. In the oral glucose tolerance test, mean fasting glucose levels (79.6 +/- 1.4 mg/dl) rose to maximum levels (157.3 +/- 4.3 mg/dl) at 30 min in hyperthyroid children which were significantly higher than the levels in control subjects (p less than 0.01). The maximum levels of glucose fell slowly and returned to fasting levels at 180 min. In this test, plasma insulin levels increased from basal levels (12.7 +/- 1.9 microU/ml) to maximum levels (120.8 +/- 22.1 microU/ml) at 30 min in the prepubertal age group of hyperthyroidism. On the other hand, in the pubertal age group of hyperthyroidism, maximum levels of insulin were observed at 60 min, but not at 30 min. These maximum levels of insulin of both hyperthyroid age groups were significantly higher than those in the control subjects (p less than 0.05, p less than 0.01 respectively). There was no difference in insulin-glucose ratio at 30 min (delta IRI/delta BG) and insulinogenic index (I.I.) at 0 to 60 min between these two groups of hyperthyroid children and control subjects. However, I.I. at 0 to 120 min and 0 to 180 min decreased significantly in the pubertal age group of hyperthyroidism as compared with those in the control group (p less than 0.05, p less than 0.02 respectively). In the oral glucose tolerance test, plasma glucagon levels decreased from basal levels (74.1 +/- 4.3 pg/ml) to minimum levels (36.4 +/- 4.7 pg/ml) at 90 min in hyperthyroidism, which were significantly lower than those in the controls (p less than 0.05). However, there was no difference in -epsilon delta IRG/epsilon delta BG (cumulative glucagon response/cumulative glucose response) between the subjects with hyperthyroidism and the controls. On the other hand, lower responses of blood glucose, insulin, glucagon and growth hormone to arginine were observed in subjects with hyperthyroidism than in the controls. Moreover in the insulin tolerance test, there was no difference in glucagon and growth hormone response between the subjects with hyperthyroidism and the controls. Thus our conclusions are as follows: A marked increase in blood glucose after oral glucose load was observed in spite of normal insulin-glucose ratio in hyperthyroid children, suggesting the existence of peripheral insulin resistance.(ABSTRACT TRUNCATED AT 400 WORDS)