The relationship between subnormal peak-stimulated growth hormone levels and auxological characteristics in obese children

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 g/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-naive 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 g/L had significantly lower value for natural log (In) 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 g/L, and 23 times more likely to have a peak GH of <7 g/L (OR = 23.3, p = 0.021). There was a significant inverse relationships between BMI SDS and the In of peak GH (beta = 0.40, r(2) = 0.26, p = 0.001), but not for BMI SDS vs. GV SDS, In peak GH vs. BA, or In peak GH vs. GV SDS. Conclusion: Subnormal peak GH levels in obese prepubertal children are not associated with unique pre-GHST auxological characteristics.