The Relationship between Subnormal Peak-Stimulated Growth Hormone Levels and Auxological Characteristics in Obese Children

Abstract

Context: The hypothesis that obese children are overdiagnosed with growth hormone deficiency (GHD) has not been adequately investigated in the context of adiposity-related differences in auxology.Aim: To investigate the differences in auxological parameters between short, prepubertal, obese children, and normal-weight peers who underwent growth hormone stimulation testing (GHST).Hypothesis: Over-weight/obese children with GHD [peak growth hormone (GH) < 10 μg/L] will have higher values for growth velocity (GV) standard deviation score (SDS), bone age minus chronological age (BA − CA), and child height SDS minus mid-parental height (MPTH) SDS when compared to normal-weight GHD peers.Subjects and Methods: A retrospective review of anthropometric and provocative GHST data of 67 prepubertal, GH-naïve children of age 10.21 ± 2.56 years (male n = 45, age 10.8 ± 2.60 years; female n = 22, age 8.94 ± 2.10). Inclusion criteria: GHST using arginine and clonidine. Exclusion criteria: hypopituitarism, abnormal pituitary magnetic resonance imaging scan, syndromic obesity, or syndromic short stature. Data were expressed as mean ± SD.Results: The over-weight/obese children with peak GH of <10 μg/L had significantly lower value for natural log (ln) peak GH (1.45 ± 0.09 vs. 1.83 ± 0.35, p = 0.022), but similar values for GV SDS, insulin-like growth factor-I, insulin-like growth factor binding protein-3, bone age, BA − CA, MPTH, and child height SDS minus MPTH SDS compared to normal-weight peers with GHD. After adjusting for covariates, the over-weight/obese children (BMI ≥ 85th percentile) were >7 times more likely than normal-weight subjects (BMI < 85th percentile) to have a peak GH of <10 μg/L, and 23 times more likely to have a peak GH of <7 μg/L (OR = 23.3, p = 0.021). There was a significant inverse relationships between BMI SDS and the ln of peak GH (β = −0.40, r2 = 0.26, p = 0.001), but not for BMI SDS vs. GV SDS, ln peak GH vs. BA, or ln peak GH vs. GV SDS.Conclusion: Subnormal peak GH levels in obese prepubertal children are not associated with unique pre-GHST auxological characteristics.

Growing Up with Type 1 Narcolepsy: Its Anthropometric and Endocrine Features

“…Twenty-three children had GH levels after stimulation 37 below the current cutoff for GH deficiency, 33 suggesting an effect on pituitary GH secretion, despite normal IGF1 levels. This finding allows us to speculate that BMI alterations per se can modify the GH response to stimulation tests, 38 and the NT1nocturnal sleep disruption might be responsible for the altered GH secretion to stimulation tests. Further studies on spontaneous circadian GH secretion in NT1 children will hopefully add knowledge to the role and cause of GH-modified secretion during puberty.…”

Growth Hormone Stimulation Tests in Children with Kabuki Syndrome

“…Abdominal adiposity is an important negative determinant of GH secretion [23,24]. One study pointed out that adiposity accounts for about 20% of the variability in peak GH response [25].…”

Impact of body mass index on growth hormone stimulation tests in children and adolescents: a systematic review and meta-analysis

“…Most studies used a radioimmunoassay to measure GH in plasma or serum [26-30,32-34, 37-43,45-48,50-52,54-57,60-66,69, 71-77,79]. In more recent studies, chemiluminescence or enzyme-linked immunometric assays were used [24,25,35,36,44,49,67,70,80,81]. Five studies mentioned the use of calibrated GH assays [24,33,57,61,62].…”

“…In more recent studies, chemiluminescence or enzyme-linked immunometric assays were used [24,25,35,36,44,49,67,70,80,81]. Five studies mentioned the use of calibrated GH assays [24,33,57,61,62]. Thirty-two studies pre-specified a cutoff value for inadequate peak GH response.…”

“…The second category of studies investigated the impact of BMI on peak GH values in children referred for short stature to pediatric endocrinology clinics [24,42,43,49,57,67,78,79]. These cohorts included predominantly pre-pubertal children, with more than 70% prepubertal participants in seven out of eight studies (range 54-100%).…”