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Variability of growth hormone response to pharmacological and sleep tests performed twice in short children
1Department of Pediatrics, University of Bologna, Italy.
Insights
The overnight sleep test for growth hormone (GH) is more reliable than pharmacological tests. Repeating the sleep test helps prevent misinterpreting GH secretion levels in children with short stature.
Area of Science:
- Pediatric Endocrinology
- Growth Hormone Physiology
Background:
- Short stature in children can be caused by growth hormone (GH) deficiency.
- Accurate assessment of GH secretion is crucial for diagnosis and treatment.
Purpose of the Study:
- To compare the reliability of overnight sleep tests versus pharmacological stimulation tests for assessing GH secretion in children.
- To determine the most consistent parameters for GH assessment.
Main Methods:
- Forty-nine children with short stature were divided into two groups.
- Group 1 underwent repeated arginine and sleep tests; Group 2 underwent repeated arginine and L-dopa tests.
- Coefficients of variation were calculated for various GH secretion parameters from both test types.
Main Results:
- Sleep test parameters, specifically mean GH concentration (MGHC) and area under the curve, showed significantly lower coefficients of variation than pharmacological tests.
- Pharmacological tests (arginine and L-dopa) demonstrated no significant difference in reliability between repeated administrations.
- Some children showed variable GH levels between test repetitions, highlighting potential diagnostic challenges.
Conclusions:
- Overnight sleep tests are more reproducible and reliable for assessing GH secretion in children compared to pharmacological tests.
- The MGHC and area under the curve from sleep tests are the most consistent GH assessment parameters.
- Repeating GH tests, particularly sleep tests, is recommended when GH secretion is borderline or appears deficient to avoid misdiagnosis.
Abstract:
Forty-nine children with short stature (age range, 4.1-15.9 yr) were examined. Twenty-four (group 1) were submitted twice to an arginine and a sleep test (12-h overnight GH profile). Twenty-five patients (group 2) were submitted twice to an arginine and L-dopa test. Coefficients of variation were calculated between both the results of pharmacological (peak and area under the curve) and sleep tests [mean GH concentration (MGHC), peak, area under the curve, number of peaks above 5 micrograms/L, and peak area]. In group 1 the coefficient of variation of sleep test parameters was significantly lower than that of pharmacological tests (P less than 0.01 to less than 0.001). In the sleep test the area under the curve and MGHC were the most constant parameters. Group 2 showed no difference between the coefficients of variation of the two pharmacological tests. Considering groups 1 and 2 together, the coefficients of variation of the sleep test, in particular the MGHC and area under the curve, were lower than those of the two pharmacological tests. Eight of 24 subjects in group 1 showed a low GH level in 1 series of tests, and a normal level in the other series. Five of 18 subjects in group 2 showed an abnormally low GH response to the arginine and L-dopa tests and a normal response to the 2 repeated tests. Therefore, to prevent an erroneous interpretation of the GH test results, it is very important to perform a sleep test and repeat it whenever GH secretion seems to be deficient or at the lower limits of normalcy.