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Growth hormone testing in short children and their response to growth hormone therapy
T H Lin1, R T Kirkland, B M Sherman
1Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030.
Insights
Growth hormone (GH) levels in 24-hour studies did not differentiate between normal and short children. Short children receiving GH therapy showed improved growth, indicating GH treatment benefits short stature, independent of baseline GH levels.
Area of Science:
- Pediatric Endocrinology
- Growth Hormone Physiology
- Childhood Growth Disorders
Background:
- Current methods for growth hormone (GH) testing and treatment are debated.
- Understanding GH secretory patterns in children with normal and short stature is crucial.
Purpose of the Study:
- To investigate 24-hour GH secretory patterns in children with normal and short stature.
- To evaluate the predictive value of GH levels on response to GH therapy.
- To assess the efficacy of GH therapy in short children.
Main Methods:
- Evaluated 24-hour serum GH levels in three groups: normal height, short stature with normal provocative GH tests, and short stature with subnormal provocative GH tests.
- Assessed linear growth rates before and after 6 months of GH therapy in a subset of short children.
- Correlated 24-hour GH levels with height, growth rates, and insulin-like growth factor 1.
Main Results:
- Mean 24-hour GH levels did not differ significantly between normal and short children, including those with GH deficiency.
- 24-hour GH levels did not correlate with height, growth velocity, or IGF-1 levels.
- Short children receiving GH therapy demonstrated a significant increase in linear growth velocity (mean change of 4.8 cm/yr).
- Slower baseline growth rates predicted a better response to GH therapy.
Conclusions:
- 24-hour GH levels overlap between normal and short children, challenging traditional diagnostic criteria.
- Baseline GH levels do not predict response to short-term GH therapy.
- GH therapy effectively enhances linear growth velocity in the majority of short children, particularly those with slower initial growth.
Abstract:
Because current concepts of growth hormone (GH) testing and GH treatment have become controversial, we investigated the GH secretory patterns in children with normal and short stature. Twenty-four-hour serum GH levels were evaluated in three groups of children. Group 1 was composed of children with normal height (mean height = 0.02 SD, n = 33); group 2 was composed of short children (less than 5th percentile, n = 63) with normal results on provocative GH testing; and group 3 was composed of short children (less than 5th percentile, n = 7) with subnormal results on provocative GH testing. Mean +/- SD (range) GH levels during 24-hour studies of GH secretion were 1.6 +/- 1.1 (0.5 to 5.6), 1.8 +/- 1.2 (0.6 to 6.3), and 0.9 +/- 0.4 (0.5 to 1.7) ng/ml in groups 1, 2, and 3, respectively. No statistical difference existed in mean GH levels between groups 1 and 2 or between groups 1 and 3. The mean GH concentration from 24-hour studies in group 2 children did not correlate with chronologic age, height standard deviation, growth rates, or insulin-like growth factor 1 levels. The linear growth rate of 26 of 28 children in group 2 who received GH therapy for 6 months improved by 2 cm/yr or more; the mean +/- SD growth rate was 4.0 +/- 1.3 and 8.8 +/- 2.0 cm/yr during control and treatment periods, respectively, for these 28 children. Mean GH levels from testing did not predict response to GH during 6 months of therapy. Children with slower growth rates responded better to GH therapy (p less than 0.05). We conclude that (1) in 24-hour studies, GH levels in normal children overlapped with those of short children, including those with classic GH deficiency, (2) in 24-hour studies, GH levels did not predict responses of linear growth to short-term GH treatment, nor did they correlate with children's heights or growth velocities, and (3) the majority of short children in group 2 treated with GH for 6 months had an increase in linear growth velocity, the mean +/- SD change being 4.8 +/- 2.0 cm/yr.