BACKGROUND: GH secretion is quantifiable as mean, peak, and nadir GH concentrations; degree of irregularity (approximate entropy); and spikiness (brief staccato-like fluctuations). HYPOTHESIS: Distinct GH dynamics reflect relatively distinct (combinations of) subject variables, such as gender, age, body mass index (BMI), and IGF-I concentrations. LOCATION: The study took place at a clinical translational research unit. SUBJECTS: Subjects included 100 healthy adults ages 20-77 yr (59 women and 41 men), BMI 18-42 kg/m(2), and IGF-I 9.2-38 nmol/liter. MEASURES: Immunofluorometric GH assay was done on 10-min samples collected for 24 h. RESULTS: Stepwise forward-selection multivariate regression analysis revealed that mean GH concentrations were simultaneously determined (overall r = 0.36; P < 0.001) by gender (higher in women, P < 0.001), BMI (negatively, P < 0.001), and IGF-I (positively, P < 0.001). Peak GH levels were influenced (r = 0.28) by both BMI (P < 0.001) and IGF-I (P = 0.001). Nadir GH values were jointly affected by gender (higher in women, P = 0.005) and BMI (negatively, P = 0.001). GH approximate entropy was triply defined (r = 0.29) by gender (greater irregularity in women, P < 0.001), age (P = 0.022), and BMI (P = 0.008) and dually (r = 0.25) by gender (P = 0.0001) and BMI (P = 0.017) if sex steroids were included. GH spikiness was determined (r = 0.29) by gender (higher in women, P = 0.0016) and BMI (positively, P = 0.0002). CONCLUSION: In healthy adults, combinations of gender, age, BMI, and IGF-I specify distinct GH dynamics, thus requiring balanced representation of these variables in comparative GH studies.
BACKGROUND: GH secretion is quantifiable as mean, peak, and nadir GH concentrations; degree of irregularity (approximate entropy); and spikiness (brief staccato-like fluctuations). HYPOTHESIS: Distinct GH dynamics reflect relatively distinct (combinations of) subject variables, such as gender, age, body mass index (BMI), and IGF-I concentrations. LOCATION: The study took place at a clinical translational research unit. SUBJECTS: Subjects included 100 healthy adults ages 20-77 yr (59 women and 41 men), BMI 18-42 kg/m(2), and IGF-I 9.2-38 nmol/liter. MEASURES: Immunofluorometric GH assay was done on 10-min samples collected for 24 h. RESULTS: Stepwise forward-selection multivariate regression analysis revealed that mean GH concentrations were simultaneously determined (overall r = 0.36; P < 0.001) by gender (higher in women, P < 0.001), BMI (negatively, P < 0.001), and IGF-I (positively, P < 0.001). Peak GH levels were influenced (r = 0.28) by both BMI (P < 0.001) and IGF-I (P = 0.001). Nadir GH values were jointly affected by gender (higher in women, P = 0.005) and BMI (negatively, P = 0.001). GH approximate entropy was triply defined (r = 0.29) by gender (greater irregularity in women, P < 0.001), age (P = 0.022), and BMI (P = 0.008) and dually (r = 0.25) by gender (P = 0.0001) and BMI (P = 0.017) if sex steroids were included. GH spikiness was determined (r = 0.29) by gender (higher in women, P = 0.0016) and BMI (positively, P = 0.0002). CONCLUSION: In healthy adults, combinations of gender, age, BMI, and IGF-I specify distinct GH dynamics, thus requiring balanced representation of these variables in comparative GH studies.
Authors: Ferdinand Roelfsema; Alberto M Pereira; Daniel M Keenan; Johannes D Veldhuis; Johannes A Romijn Journal: J Clin Endocrinol Metab Date: 2008-08-05 Impact factor: 5.958
Authors: Johannes D Veldhuis; Kristi L Mielke; Mihaela Cosma; Cacia Soares-Welch; Remberto Paulo; John M Miles; Cyril Y Bowers Journal: J Clin Endocrinol Metab Date: 2008-12-16 Impact factor: 5.958
Authors: Peter Y Liu; Daniel M Keenan; Petra Kok; Vasantha Padmanabhan; Kevin T O'Byrne; Johannes D Veldhuis Journal: Am J Physiol Endocrinol Metab Date: 2009-06-16 Impact factor: 4.310
Authors: Johannes D Veldhuis; Ferdinand Roelfsema; Ali Iranmanesh; Bernard J Carroll; Daniel M Keenan; Steven M Pincus Journal: J Clin Endocrinol Metab Date: 2009-09-15 Impact factor: 5.958
Authors: Ferdinand Roelfsema; Alberto M Pereira; Nienke R Biermasz; Johannes D Veldhuis Journal: J Clin Endocrinol Metab Date: 2014-07-11 Impact factor: 5.958