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[Variability of growth hormone response to repeated stimulation tests in children of normal height]
H L Fideleff1, H R Boquete, N Saskyn
1Unidad de Endocrinología, Hospital Municipal T. Alvarez, Buenos Aires.
Insights
This study found that both the clonidine and exercise-propranolol tests are reproducible for measuring growth hormone (GH) in children. These tests offer reliable options for diagnosing growth disorders.
Area of Science:
- Pediatric Endocrinology
- Growth Hormone Physiology
- Diagnostic Test Reproducibility
Background:
- False negatives in short stature evaluation are common.
- Variability in 24-hour growth hormone (GH) studies affects diagnosis.
- Need for reproducible pharmacological tests in children.
Purpose of the Study:
- To assess the reproducibility of the clonidine test for GH stimulation.
- To evaluate the reproducibility of the exercise-propranolol test for GH stimulation.
- To compare test-retest reliability in normal prepubertal children.
Main Methods:
- Forty prepubertal children with normal growth parameters were enrolled.
- Group I (n=20) underwent the clonidine test (100 µg/m²) with GH measurements at 0, 60, and 90 minutes.
- Group II (n=20) underwent the exercise-propranolol test (0.5 mg/kg) with basal and post-exercise GH measurements. Both tests were repeated after one week.
Main Results:
- No significant differences were observed in basal or maximal GH response between the first and second tests for the clonidine group (Group I).
- Similarly, no significant differences were found in basal or maximal GH response between the first and second tests for the exercise-propranolol group (Group II).
- Wilcoxon's test confirmed the lack of significant variations in GH measurements for both tests upon repetition.
Conclusions:
- The clonidine stimulation test demonstrates good reproducibility in normal prepubertal children.
- The exercise-propranolol stimulation test also shows reliable reproducibility in this population.
- Both pharmacological tests are suitable for repeated use in evaluating growth hormone secretion in children.
Abstract:
The presence of false negatives in the evaluation of patients with short stature and the variability of 24 hour growth hormone (GH) physiological studies in the normal population are well known. Therefore the reproducibility of two widely used pharmacological test was studied in normal children. Forty prepuberal children were evaluated (34 boys and 6 girls), with chronological ages ranging from 2 years 11 months to 12 years 11 months (mean: 9 years 1 month), bone ages from 3 years 2 months to 12 years 6 months (mean: 8 years 4 months) and with normal stature and growth velocity (SDS > -2) and normal body mass index (BMI < 25). Clonidine test was performed (100 micrograms/m2 surface) measuring GH (ng/ml) 0,06 and 90 min in 20 patients (Group I). Exercise-Propranolol test was performed (0,5 mg/kg weight) with basal and post-exercise GH measurements in 20 patients (Groups II). The tests were repeated at one week intervals and each child was his own control. Group I showed (mean +/- SD): 1st test: B = 1.78 +/- 1.59, Max Resp = 13.16 +/- 8.34; 2nd test: B = 1.17 +/- 0.51, Max Resp = 15.12 +/- 8.09. Group II showed (mean +/- SD): 1st test: B = 1.38 +/- 0.58, Max Resp 16.97 +/- 9.69; 2nd test: B = 1.54 +/- 1.16, Max Resp = 13.49 +/- 7.81. Wilcoxon's test did not show significant differences when comparing B vs B and Max Resp vs Max Resp in both groups.(ABSTRACT TRUNCATED AT 250 WORDS)