ESPE Abstracts

It has been established that a random growth hormone (rGH) level can be obtained and is useful within the first 28 days of life for establishing a diagnosis of congenital growth hormone deficiency (cGHD). However, it remains unclear if weight-for-length (WfL), a surrogate for adiposity, impacts these levels, similar to how body mass index in older subjects impacts peak growth hormone levels derived from provocation testing. The objective of this study is to determine the impact of weight for WfL on rGH levels obtained during the first 28 days of life. This is a retrospective chart review of subjects who had rGH levels collected during the first 28 days of life. Indications for testing were: hypoglycemia, jaundice, micropenis, abnormal central nervous system imaging and other miscellaneous findings. Deceased subjects and those for whom a WfL could not be calculated due to length < 45 cm were excluded. The primary measure was rGH level. Length, weight, gestational age at delivery, and sex data were also collected. Univariate analyses were performed using Pearson correlation coefficient. Multivariate linear regression analysis was used to determine independent predictors of rGH levels. Covariates such as age, sex, gestational age at delivery which were suspected as potentially having an impact of rGH levels were entered into the model. The study included 121 neonates with mean age 7.33 +/- 5.40 days, 100 (83%) were born at term gestation and 92 (76%) males. The 2 most common reasons for rGH level testing were hypoglycemia (43.8%) and abnormal central nervous system imaging (25.6%). In the univariate regression WfL z-score was not associated with rGH levels, p =0.0773. Using multivariate analysis, no other variables were found to be significant (all had P-value >0.1) For neonates who undergo testing based on a suspicion of cGHD, rGH levels do not appear to be impacted by WfL and can be interpreted without caution. This also highlights the contribution of in utero factors on neonatal growth hormone production rather than adiposity which impacts GH levels later in life.