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The relationship between height velocity and growth hormone secretion in short prepubertal children
P Hindmarsh1, P J Smith, C G Brook
1Endocrine Unit, Middlesex Hospital, London, UK.
Insights
Growth hormone (GH) pulse amplitude is key for height velocity in children. This study shows GH secretion is continuous, suggesting exogenous GH may help short children grow faster.
Area of Science:
- Pediatric Endocrinology
- Growth Hormone Physiology
- Child Development
Background:
- Assessing growth hormone (GH) secretion is crucial for diagnosing growth disorders in children.
- Previous methods for evaluating GH secretion have shown limitations in clearly distinguishing between GH sufficiency and insufficiency.
- Understanding the relationship between spontaneous GH secretion and linear growth is essential for effective treatment strategies.
Purpose of the Study:
- To investigate the relationship between spontaneous growth hormone (GH) secretion and height velocity in short prepubertal children.
- To determine the most significant parameter of GH secretion (e.g., pulse amplitude vs. duration) influencing height velocity.
- To evaluate the utility of GH responses to insulin-induced hypoglycemia and serum IGF-I levels in assessing growth potential.
Main Methods:
- Conducted 24-hour ambulatory GH profiles in 50 short prepubertal children (ages 5.2-12.9 years).
- Measured height velocity standard deviation scores (SDS) to quantify growth rate.
- Analyzed the correlation between height velocity SDS and parameters of spontaneous GH secretion, including pulse amplitude and duration.
Main Results:
- An asymptotic relationship was found between height velocity SDS and spontaneous GH secretion, best described by GH pulse amplitude.
- GH pulse duration contributed minimally to the relationship between height velocity and GH secretion.
- Continuous distribution of GH secretion was observed, with no clear cutoff for GH insufficiency versus sufficiency; overlap also seen in GH response to hypoglycemia and IGF-I levels.
Conclusions:
- Height velocity, a determinant of final height, is primarily controlled by growth hormone (GH) pulse amplitude.
- The continuous nature of GH secretion and overlap in diagnostic tests indicate limitations in current assessment methods.
- Exogenous GH administration may be beneficial for accelerating growth in short children growing parallel to the third height centile.
Abstract:
We have performed 24 h growth hormone (GH) profiles in 50 short prepubertal children aged between 5.2 and 12.9 years, growing with height velocity standard deviation scores (SDS) between 0.4 and -3.9. There was an asymptotic relationship between height velocity and spontaneous GH secretion described by the equation: height velocity SDS = A-B(e-cx), where A, B and C are constants and x is a measure of spontaneous GH secretion. We considered GH pulse amplitude to be the better description of spontaneous GH secretion as duration of the GH pulse (the time component of area under the curve) contributed little to the relationship between height velocity and area under the pulse. The distribution of GH secretion was continuous and there was no dividing point between GH insufficiency and sufficiency. Similar overlap was observed when the results of GH responses to insulin induced hypoglycaemia were considered; 14% of slowly growing children (height velocity SDS less than -0.8), had a response greater than 15 mU/l. Likewise serum IGF-I concentrations could not clearly separate slowly growing children from normal individuals. We conclude that height velocity, which ultimately determines height achieved, is controlled predominantly by GH pulse amplitude. The findings suggest that short normal children growing along or parallel to the third height centile could be made to grow faster by the administration of exogenous GH.