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The relationship of growth rate, plasma growth hormone (GH) concentration, and GH-binding protein
M Phillip1, S A Chalew, R J McCarter
1Department of Pediatrics, University of Maryland School of Medicine, Baltimore, 21201, USA.
Insights
Growth hormone-binding protein (GHBP) and GH secretion influence linear growth in children. In children with normal stature, higher GH levels correlated with growth, while higher GHBP levels correlated with decreased growth.
Area of Science:
- Pediatrics
- Endocrinology
- Growth Biology
Background:
- Growth hormone (GH)-binding protein (GHBP) and GH secretion are key factors in pediatric linear growth.
- Understanding their interplay is crucial for diagnosing and managing growth disorders.
Purpose of the Study:
- To investigate the relationship between GHBP, GH secretion, and linear growth rate in children.
- To determine if height status modifies the association between GHBP, GH, and growth.
Main Methods:
- Measured GHBP activity, peak stimulated GH (PKGH), and 24-hour integrated GH concentration (ICGH) in 76 children.
- Calculated growth rate standard deviation score (GRSD) and height standard deviation score (HGTSD).
- Utilized multiple regression analysis, stratifying by HGTSD.
Main Results:
- In children with normal stature (HGTSD > -2), GRSD increased with GH concentration (PKGH and ICGH) and decreased with higher GHBP levels.
- In children with severe short stature (HGTSD ≤ -2), GRSD was not predictable by GHBP, GH secretion, or height status.
- The relationship between GHBP and growth was dependent on height status.
Conclusions:
- GHBP and GH levels may be important predictors of growth rate in children with normal stature.
- The predictive role of GHBP and GH secretion on growth rate appears limited in children with severe short stature.
- Height status is a critical factor modulating the impact of GHBP and GH on linear growth.
Abstract:
Growth hormone (GH)-binding protein (GHBP) and GH secretion are potential mediators of linear growth in children. To study the relationship between these variables, we measured GHBP activity, peak stimulated GH (PKGH), and 24-hour integrated GH concentration (ICGH) in 76 children referred for evaluation of growth. Linear growth was expressed as an age- and sex-specific growth rate standard deviation score (GRSD), which was calculated from sequential height measurements in the 6-month period immediately before GH testing. Using multiple regression models, we found that the relationship between GHBP and growth (GRSD) depended on height (height standard deviation [HGTSD] expressed as an age- and sex-specific z score) controlling for ICGH or PKGH. In further analysis of this relationship, we divided the subjects by HGTSD in subsequent analyses. In 19 children of normal stature (HGTSD > -2), GRSD increased with GH concentration (measured both as PKGH and ICGH: P <.013,R2 = .56) but decreased with higher levels of GHBP (P < .005,R2 = .62). In contrast, for 57 subjects with severe short stature (HGTSD < or = -2), GRSD could not be predicted from GHBP, GH secretion, HGTSD, or interaction involving these variables. These data suggest the hypothesis that under normal conditions, GHBP and GH level may be important predictors of growth rate in children.