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Two types of growth hormone rhythm in boys with constitutional short stature
R Keret1, I E Ashkenazi, M Wasserman
1Pediatric Endocrinology & Diabetes Research Unit, Schneider Children's Medical Center, Israel.
Insights
Growth hormone (GH) secretion patterns impact growth in constitutionally short children (CSS). Children with a 24-hour circadian rhythm (CIR) showed greater GH secretion and were taller than those lacking this rhythm (NCIR).
Area of Science:
- Pediatric Endocrinology
- Growth Hormone Physiology
- Chronobiology
Background:
- Constitutionally short children (CSS) exhibit variations in growth hormone (GH) secretion.
- Understanding the temporal and quantitative aspects of pulsatile GH secretion is crucial for CSS growth.
- Previous studies have not fully elucidated the role of GH secretory patterns in CSS.
Purpose of the Study:
- To investigate the relationship between temporal and quantitative changes in pulsatile GH secretion and growth in CSS.
- To compare GH secretion patterns between CSS children with and without a 24-hour circadian rhythm.
- To determine if GH pulse magnitude or number is more critical for growth differences in CSS.
Main Methods:
- Continuous 24-hour plasma GH monitoring at 30-minute intervals in 23 prepubertal boys.
- Analysis using best fit (BFT) cosinor for rhythm parameters and Pulsar for peak detection.
- Categorization of children into circadian rhythm (CIR) and non-circadian rhythm (NCIR) groups based on GH patterns.
Main Results:
- Thirteen of 23 GH secretion patterns showed significant 24-hour rhythms; ultradian rhythms were present in all patients.
- Children lacking a 24-hour rhythm (NCIR) were significantly shorter than those with a circadian rhythm (CIR).
- CIR boys exhibited significantly higher 24-hour GH secretion, particularly during sleep, compared to NCIR boys.
Conclusions:
- GH pulse magnitude, not pulse number, likely explains quantitative GH differences in CSS.
- A lack of 24-hour GH rhythmicity and reduced nocturnal pulsatility may contribute to short stature in CSS.
- Circadian regulation of GH secretion is important for normal growth in constitutionally short children.
Abstract:
The relationship between temporal and quantitative changes in pulsatile growth hormone (GH) secretion and growth of constitutionally short children (CSS) was studied in 19 prepubertal boys and 4 with early adrenarche aged 7.8 to 14 years. Continuous plasma GH monitoring was performed at 30 minutes intervals during 24 hours. The data were analysed by single and serial best fit (BFT) cosinor analysis for rhythm parameters and the Pulsar peak detection program for determining pulsatile properties. The pulsatile patterns were expressed in mean GH concentration, area under the curve, mean pulse area and maximal pulse height but not in the number of pulses. Thirteen out of 23 patterns exhibited significant 24-h compatible rhythms. The studied cohort was divided into two groups, those who exhibited the 24-h circadian rhythm (CIR) and those who lacked it (NCIR). Ultradian 2.5-4 h rhythms were observed in all patients. The NCIR children were significantly shorter than the CIR group (p = 0.017). The CIR boys secreted a significantly higher (p = 0.01) amount of GH during the 24-h span, most of which was during sleep. Our data indicate that the magnitude of pulses rather than their number is responsible for the quantitative differences observed between the two groups of boys with CSS. It is suggested that a lack of 24-h rhythmicity and the associated reduced nocturnal pulsatility play a role in the manifestation of short stature.