Analyses of 24-Hour Growth Hormone Profiles in Children: Relation to Growth*

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)

Nocturnal Release of Immunoreactive Growth Hormone-Releasing Hormone and Growth Hormone in Normal Children

“…With this method it is possible to get an idea of true nocturnal integrated GH and ir-GHRH secretion. Discrete and integrated sampling has been compared in a recent study and no obvious blunting or widening of the peaks using an integrated sampling technique was found (24). .…”

Clinical Usefulness of Urinary Growth Hormone Measurements in Normal and Short Children According to Different Expressions of Urinary Growth Hormone Data

“…Twenty-four-h endogenous GH secretion has been reported to correlate with other parameters related to growth, such as IGF-I (25), growth velocity (27), chronologic age (24), and SDS for height (28). Some authors have demonstrated correlations between UGH and IGF-I (14, 16) and UGH and growth velocity (15).…”

Nocturnal Serum Growth Hormone Concentration is not Augmented by Short-Term Testosterone Infusion in Pubertal Boys

“…Albertsson-Wikland and Rosberg (27) found a nonlinear correlation between ht and mean GH concentration for pubertal children (r = 0.36) but the correlation was much more striking for the prepubertal children where a linear correlation (r = 0.69) was found. A correlation of mean GH and ht was not found in our pubertal subjects, perhaps due to our small sample size or the presence of constitutional growth delay.…”