Mabel Yau1, Elizabeth Chacko2, Molly O Regelmann3, Rachel Annunziato4, Elizabeth J Wallach2, Dennis Chia5, Robert Rapaport2. 1. Division of Pediatric Endocrinology and Diabetes, Icahn School of Medicine at Mount Sinai, New York, New York, USA, mabel.yau@mssm.edu. 2. Division of Pediatric Endocrinology and Diabetes, Icahn School of Medicine at Mount Sinai, New York, New York, USA. 3. Division of Pediatric Endocrinology and Diabetes, Children's Hospital at Montefiore, Bronx, New York, USA. 4. Fordham University, Bronx, New York, USA. 5. Division of Pediatric Endocrinology, UCLA David Geffen School of Medicine, Los Angeles, California, USA.
Abstract
BACKGROUND/AIMS: Studies are lacking regarding the timing of peak growth hormone (PGH) response. We aim to elucidate the timing of PGH response to arginine and levodopa (A-LD) and evaluate the influence of body mass index (BMI) and other metabolic parameters on PGH. METHODS: During growth hormone (GH) stimulation testing (ST) with A-LD, serum GH was measured at baseline and every 30 min up to 180 min. The PGH cut-off was defined as <10 ng/mL. IGF-1, IGF BP3, BMI, and metabolic parameters were obtained in a fasting state at baseline. RESULTS: In the 315 tested children, stimulated PGH levels occurred at or before 120 min in 97.8% and at 180 min in 2.2%. GH area under the curve (AUC) positively correlated with PGH in all patients and with IGF-1 in pubertal males and females. BMI negatively correlated with PGH in all subjects. GH AUC negatively correlated with HOMA-IR and total cholesterol. CONCLUSION: We propose termination of the GH ST with A-LD at 120 min since omission of GH measurement at 180 min did not alter the diagnosis of GH deficiency based on a cut-off of < 10 ng/mL. BMI should be considered in the interpretation of GH ST with A-LD. The relationships between GH AUC and metabolic parameters need further study.
BACKGROUND/AIMS: Studies are lacking regarding the timing of peak growth hormone (PGH) response. We aim to elucidate the timing of PGH response to arginine and levodopa (A-LD) and evaluate the influence of body mass index (BMI) and other metabolic parameters on PGH. METHODS: During growth hormone (GH) stimulation testing (ST) with A-LD, serum GH was measured at baseline and every 30 min up to 180 min. The PGH cut-off was defined as <10 ng/mL. IGF-1, IGF BP3, BMI, and metabolic parameters were obtained in a fasting state at baseline. RESULTS: In the 315 tested children, stimulated PGH levels occurred at or before 120 min in 97.8% and at 180 min in 2.2%. GH area under the curve (AUC) positively correlated with PGH in all patients and with IGF-1 in pubertal males and females. BMI negatively correlated with PGH in all subjects. GH AUC negatively correlated with HOMA-IR and total cholesterol. CONCLUSION: We propose termination of the GH ST with A-LD at 120 min since omission of GH measurement at 180 min did not alter the diagnosis of GH deficiency based on a cut-off of < 10 ng/mL. BMI should be considered in the interpretation of GH ST with A-LD. The relationships between GH AUC and metabolic parameters need further study.