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Growth hormone secretory patterns in children with short stature
Insights
Spontaneous growth hormone (GH) secretion varies widely in growth-retarded children. Nocturnal GH levels, not 24-hour averages, better indicate GH reserve, especially during puberty.
Area of Science:
- Pediatric Endocrinology
- Growth Hormone Physiology
- Child Development
Background:
- Growth retardation in children necessitates understanding spontaneous growth hormone (GH) secretion patterns.
- Assessing GH secretion is crucial for diagnosing and managing growth disorders.
Purpose of the Study:
- To evaluate spontaneous GH secretion in growth-retarded children with stimulated GH levels > 10 ng/mL.
- To determine if GH levels during sleep or over 24 hours are more indicative of GH secretion abnormalities.
Main Methods:
- Measured GH levels every 30 minutes for 24 hours in 50 growth-retarded children (ages 2.7-17).
- Assessed correlations between 24-hour GH, sleep-induced GH peaks, somatomedin C (SmC), age, bone age, and growth rate.
- Compared GH secretion in pubertal versus prepubertal children.
Main Results:
- Mean 24-hour GH concentration varied widely (1.2-7.7 ng/mL) and was higher in pubertal children.
- GH concentration during sleep was significantly higher than during wakeful hours.
- Serum SmC correlated with age and bone age, and with 24-hour GH in prepubertal children, but SmC strongly correlated with growth rate only in pubertal children.
- Growth velocity increased with GH therapy irrespective of baseline 24-hour GH levels.
Conclusions:
- Spontaneous GH secretion shows significant variability in growth-retarded children, with higher levels during puberty.
- Nocturnal GH peaks are more informative than 24-hour GH concentrations for evaluating GH secretion.
- In puberty, SmC reflects sexual development more than GH reserve; GH therapy benefits short children regardless of GH deficiency status.
Abstract:
To assess whether growth-retarded children with a stimulated growth hormone (GH) level greater than 10 ng/mL have an abnormality in spontaneous GH secretion, we measured GH levels every half hour for 24 hours in 50 children 2.7 to 17 years of age. Growth rate was subnormal in all. Mean 24-hour GH concentration ranged from 1.2 to 7.7 ng/mL, and was significantly greater in pubertal than in prepubertal children (P less than 0.01). In both groups, GH concentration during sleep was significantly greater than during wakeful hours (P less than 0.0005); 24-hour GH concentration correlated significantly with sleep-induced GH peak. A decrease in 24-hour GH concentration and sleep-induced GH peak were noted in four pubertal children with stimulated GH less than 15 ng/mL. A progressive and significant increase in somatomedin C (SmC) level was noted with increasing age and sexual development. No correlations were found between 24-hour GH concentration and rate of growth, age, or bone age. Serum SmC values correlated significantly with age and bone age (P less than 0.01), and with 24-hour GH concentration only in prepubertal children (P less than 0.05). A strong correlation between SmC and growth rate was noted only in pubertal children (P less than 0.01). Growth velocity increased significantly during GH therapy regardless of the 24-hour GH concentration. Our results indicate that in children with growth retardation there is a wide variation in 24-hour GH concentration and a significant increase in GH concentration during puberty; the GH concentration during nocturnal sleep, rather than an entire 24-hour GH concentration, can be used for evaluation; during puberty the SmC level reflects sexual development more than GH reserve; and GH therapy appears to increase growth velocity in both non-GH-deficient and partially GH-deficient short children.