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Analyses of 24-hour growth hormone profiles in children: relation to growth
K Albertsson-Wikland1, S Rosberg
1Department of Pediatrics II, University of Göteborg, Sweden.
Insights
Growth hormone (GH) secretion in children correlates with height, with 24-hour sampling essential for accurate assessment. A 30-minute sampling interval is a practical compromise for measuring GH levels.
Area of Science:
- Pediatric endocrinology
- Growth hormone dynamics
- Biomarker assessment
Background:
- Accurate assessment of growth hormone (GH) secretion is crucial for diagnosing growth disorders in children.
- Understanding the relationship between GH levels and physical growth parameters like height is essential for clinical practice.
Purpose of the Study:
- To investigate the correlation between 24-hour GH secretion and height in prepubertal and pubertal children.
- To evaluate the impact of different blood sampling frequencies and durations on the accuracy of GH secretion assessment.
Main Methods:
- Collected integrated 20-minute blood samples over 24 hours from 127 children (88 prepubertal, 39 pubertal).
- Measured plasma GH using a polyclonal radioimmunoassay (RIA) method.
- Analyzed GH profiles using the Pulsar computer program and simulated various sampling intervals (20, 30, 40, 60 minutes) and durations (6, 8, 12, 24 hours).
Main Results:
- A 30-minute sampling interval provided results comparable to 20-minute sampling, while 60-minute sampling led to increased baseline GH and decreased peak GH (AUCb).
- Shorter sampling periods (less than 24 hours) resulted in a decrease in AUCb and an increase in baseline GH, indicating the necessity of full 24-hour sampling.
- A strong positive correlation was found between height (SD score) and 24-hour GH AUCb in prepubertal children (r=0.69, P<0.001).
- A nonlinear correlation was observed between height and 24-hour GH AUCb in pubertal children (r=0.36, P<0.05).
Conclusions:
- 24-hour GH sampling is necessary for accurate assessment of GH secretion in children.
- A 30-minute sampling interval represents a practical compromise for GH measurement.
- Childhood height is significantly correlated with 24-hour GH secretion, particularly in prepubertal individuals.
Abstract:
The relationship between height and amount of GH measured during a 24-h period was studied in 127 children who were growing at different rates. Of the children, 88 were prepubertal (3-16 yr old) and 39 were pubertal (10-16 yr old). The height of each child was expressed as the SD score, i.e. height in relation to the sex- and age-matched Swedish reference groups, and spontaneous GH secretion was estimated by taking integrated 20-min blood samples for a 24-h period, i.e. 72 samples/child. In a few children, discrete samples were taken in parallel with the integrated 20-min samples with virtually the same results. Plasma GH was estimated in each sample using a polyclonal RIA method. To compare different 24-h GH profiles, the profiles were analyzed using a computer program (Pulsar). One objective of the study was to determine if less frequent sampling and/or shorter sampling periods yielded the same information as that obtained by 20-min sampling for the whole 24-h period. To determine if less frequent sampling provided the same information as that obtained by the 20-min period, we simulated 40- and 60-min periods by pooling two or three consecutive samples. No difference was found between 20- and 40-min sampling, but with 60-min sampling the mean calculated baseline plasma GH concentrations increased, and the GH concentration within peaks [the area under the curve above the baseline (AUCb)] decreased markedly. A 30-min sampling interval thus seems to be a valid practical compromise. To determine if sampling periods shorter than 24 h provided the same information, we divided the profiles, which started at 0900 h, into two 12-h, three 8-h and four 6-h periods. A graded decrease in AUCb and a corresponding increase in the baseline was found with the shorter periods, indicating that the whole 24-h period is necessary for GH sampling. Another objective of the study was to determine whether there was a correlation between 24-h GH secretion and the height, age, and sex of the children. In the prepubertal children, the height (in SD scores) was highly correlated (r = 0.69; P less than 0.001) with GH AUCb during the 24-h period. Height also correlated with AUCb estimated over shorter time periods; the correlation diminished with decreasing time. In the pubertal children, a nonlinear correlation (r = 0.36; P less than 0.05) was found between height and 24-h GH (AUCb).(ABSTRACT TRUNCATED AT 400 WORDS)