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Defective response of plasma growth hormone to growth hormone releasing factor in growth hormone deficient children
1Department of Pediatrics, Veterans General Hospital, Taipei, Taiwan, R.O.C.
Insights
The growth hormone releasing factor (GRF) test safely identifies growth hormone (GH) deficiency origins. GRF injections reveal differences in GH response between normal children and those with GH deficiency dwarfism.
Area of Science:
- Pediatric Endocrinology
- Hormone Research
- Diagnostic Medicine
Background:
- Establishing reference patterns for plasma growth hormone (GH) response is crucial for diagnosing GH deficiency.
- Growth hormone releasing factor (GRF) (1-29)NH2 is a synthetic peptide used to stimulate GH secretion.
- Idiopathic GH deficient dwarfism requires accurate diagnostic tools for determining the level of deficiency.
Purpose of the Study:
- To establish the reference plasma GH response pattern to GRF (1-29)NH2 in normal children.
- To evaluate the plasma GH response to GRF (1-29)NH2 in children with idiopathic GH deficient dwarfism.
- To assess the utility of the GRF test in the differential diagnosis of GH deficiency.
Main Methods:
- Intravenous injection of 1 microgram/kg GRF (1-29)NH2 to 5 normal children and 14 with GH deficient dwarfism.
- Measurement of plasma GH levels at 0, 15, 30, 45, 60, 90, and 120 minutes post-injection.
- Comparison of GRF test results with insulin-induced hypoglycemia tests and correlation with age and bone age.
Main Results:
- Normal children showed peak plasma GH levels at 45 minutes (80.31 +/- 19.28 ng/ml).
- Children with GH deficient dwarfism had significantly lower peak GH levels (13.10 +/- 10.78 ng/ml) at 45 minutes (P < 0.01).
- Three out of 14 (21.4%) GH deficient children exhibited a partial response, suggesting hypothalamic origin.
Conclusions:
- The GRF test provides a safe and effective method for assessing GH secretory capacity.
- The GRF test aids in differentiating the level of defect in GH deficiency, particularly distinguishing hypothalamic from pituitary causes.
- GRF administration may hold potential as a future therapeutic regimen for GH deficiency.
Abstract:
In an attempt to establish the reference pattern and the plasma growth hormone (GH) response to growth hormone releasing factor (GRF) (1-29)NH2, 5 normal stature with single kidney children and 14 with idiopathic GH deficient dwarfism received intravenous injections of 1 microgram/kg GRF(1-29)NH2. Plasma GH levels were measured at 0, 15, 30, 45, 60, 90, and 120 min after injection. The results showed that, first, in normal stature with single kidney children, each plasma GH reached peak level (80.31 +/- 19.28 ng/ml) at 45 min after injection. Second, the majority of those with GH deficient dwarfism also obtained maximal GH levels (13.10 +/- 10.78 ng/ml) at 45 min after injection but at significantly lower levels than the normal children (P < 0.01). To compare with that obtained after the insulin-induced hypoglycemia test, the peak GH level after GRF was higher but there was no significant correlation between them. The maximal GH level after GRF(1-29)NH2 injection did not show significant correlation with either chronological age or bone age. Third, 3 of 14 (21.4%) with GH deficient dwarfism had half response to GRF(1-29)NH2. It is reasonable to assume that out of these patients' GH deficiency is of hypothalamic origin. Therefore, GRF test is a safe and useful test for differential diagnosis of defect level in GH deficiency and may become a therapeutic regimen.