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Pulsatility of growth hormone secretion and its relation to growth
J Weill1, A Duhamel, M Dherbomez
1Pediatric Endocrine Unit, University Hospital, Lille, France.
Insights
Growth hormone (GH) secretion patterns in short children show discrepancies between provocative tests and nocturnal secretion. GH pulsatility
Area of Science:
- Pediatric Endocrinology
- Growth Hormone Physiology
- Biomedical Signal Analysis
Background:
- Assessing spontaneous growth hormone (GH) secretion is crucial for diagnosing short stature.
- Nocturnal GH secretion patterns exhibit pulsatility, which may influence growth.
- Provocative GH stimulation tests are commonly used but may not fully reflect endogenous secretion.
Purpose of the Study:
- To investigate discrepancies between provocative GH testing and spontaneous nocturnal GH secretion in short children.
- To analyze the pulsatility of nocturnal GH secretion using time-series analysis.
- To determine the relationship between GH secretion patterns and growth velocity.
Main Methods:
- 84 short children underwent nocturnal spontaneous GH secretion tests and insulin-arginine provocative tests.
- Nocturnal GH profiles were analyzed for peak (PA) and mean concentration (MC).
- Time-series analysis, including cosine function fitting and Fourier transformation, was used to evaluate GH pulsatility and identify predominant periods.
Main Results:
- Significant correlations were found between provocative GH peak (I-AP) and nocturnal GH maximal peak (PA) and mean concentration (MC), but frequent discrepancies were observed.
- Spectral analysis revealed predominant periods of approximately 180 min and secondary periods around 105-122 min in most GH secretion profiles.
- Growth velocity correlated with mean GH concentration but not with insulin-like growth factor-I or GH pulsatility indices.
Conclusions:
- Nocturnal GH secretion patterns in short children are complex and do not always align with provocative test results.
- The clinical relevance of GH pulsatility, including its specific parameters, to actual growth in humans remains unclear.
- Further research is needed to elucidate the precise role of GH pulsatility in childhood growth.
Abstract:
84 short children were submitted to nocturnal spontaneous growth hormone (GH) secretion tests and to provocative insulin-arginine tests. Discrepancies between the GH peak under the provocative test (I-AP) and nocturnal GH maximal peak (PA) and mean concentration (MC) were frequently observed, despite significant statistical correlation between I-AP and PA (r = 0.47; p < 0.02) and between I-AP and MC (r = 0.42; p < 0.02). Night profiles were evaluated by time analysis: 31 fitted a theoretical model, consisting of a cosine function of time (modelizable profiles). Spectral analysis, from Fourier transformation, indicated predominant periods after cluster analysis. The major predominant period in modelizable (n = 9) and in nonmodelizable (n = 28) profiles was close to 180 min and a secondary period was on average 122 min in modelizable (n = 20) and 105 min in nonmodelizable (n = 23) profiles. Two modelizable and two nonmodelizable profiles escaped this classification. The general, auxological and GH secretory status did not differ significantly between patients with modelizable and nonmodelizable profils. Growth velocity correlated with GH mean concentration (r = 0.36; p < 0.001), but not with plasma insulin-like growth factor-I levels nor with any of the pulsatility indices: number of peaks, main period, and pulse height index = mean GH peak/mean GH concentration. The relevance of GH pulsatility to growth is, therefore, unclear in humans.