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Correlation between cortisol and insulin-like growth factor-binding proteins (IGFBPs) under physiological conditions
C E Martinelli1, M E Yateman, A M Cotterill
1Departments of Endocrinology and Paediatrics, St. Bartholomew's Hospital, London, UK; Departments of Paediatrics and Medicine, Faculty of Medicine of Ribeirão Preto, Brazil.
Insights
This study found correlations between cortisol and IGFBP-1 and IGFBP-2 levels in children. These findings suggest that changes in insulin-like growth factor-binding proteins may be involved in the interplay between growth hormone and cortisol secretion.
Area of Science:
- Pediatric Endocrinology
- Hormonal Regulation
- Growth Factors
Background:
- Previous research noted a correlation between 24-hour spontaneous growth hormone (GH) and cortisol secretion in children.
- This led to an investigation into the relationship between diurnal cortisol variations and insulin-like growth factors (IGFs) and IGF-binding proteins (IGFBPs).
Purpose of the Study:
- To examine the relationship between physiological diurnal cortisol variation and levels of IGFs and IGFBPs.
- To understand the interplay between cortisol and IGFBPs under physiological conditions in children.
Main Methods:
- Blood samples were collected every 20 minutes over 24 hours from nine non-GH-deficient boys.
- Measurements included GH, cortisol, IGFBP-1, insulin, IGF-I, IGF-II, IGFBP-2, and IGFBP-3.
Main Results:
- No correlation was found between IGF-I or IGF-II and mean cortisol levels.
- IGFBP-1 showed circadian variation linked to cortisol rhythm, with significant positive correlations.
- IGFBP-2 levels negatively correlated with mean cortisol concentrations over the preceding 12 hours.
Conclusions:
- A clear correlation exists between cortisol and IGFBP-1 and IGFBP-2 levels.
- The interplay of spontaneous GH and cortisol secretion in children may involve alterations in IGFBP-1 and IGFBP-2 levels.
Objective:
A positive correlation between 24-h spontaneous growth hormone (GH) and cortisol secretion was previously reported in children. This observation prompted us to examine the relationship between physiological diurnal cortisol variation and the levels of insulin-like growth factors (IGFs) and IGF-binding proteins (IGFBPs) under physiological conditions.
Design And Patients:
Starting at 0800 h, blood was sampled every 20 minutes over 24 h for measurement of GH and cortisol concentration in nine non-GH- deficient boys as part of a protocol for the investigation of short stature.
Measurements:
IGFBP-1 and insulin were measured in samples drawn every 4 h over the 24-h period while IGF-I, IGF-II, IGFBP-2 and IGFBP-3 were determined in samples collected at the end of the study.
Results:
No correlation was observed between IGF-I or IGF-II and mean cortisol levels. IGFBP-1 concentrations showed a marked circadian variation that was superimposed on the circadian rhythm for cortisol while a significant positive correlation was found for single point measurements between IGFBP-1 concentrations and cortisol levels measured in the same sample (r = 0.53) or at the preceding 20 minutes (r = 0.43), 40 minutes (r = 0.47) and 2 h (r = 0.38), suggesting an interplay between cortisol and IGFBP-1. A negative correlation (r = - 0.54) was found between IGFBP-1 and insulin levels determined in the same sample. A negative correlation (r = - 0.93) was also found between IGFBP-2 levels and mean cortisol concentrations during the preceding 12 h. No correlation was observed between plasma IGFBP-3 measured by IRMA and mean cortisol levels.
Conclusion:
Our data indicate a clear correlation between cortisol and IGFBP-1 and IGFBP-2 levels. Thus, the interplay of spontaneous GH and cortisol secretion in children may involve changes in IGFBP-1 and IGFBP-2 levels.