Differential impact of age, sex XXXX hormones, and @entity28 on basal versus pulsatile growth hormone secretion in @entity1 as assessed in an ultrasensitive chemiluminescence assay.

@entity1 @entity251 @entity28 @entity2301 @entity442 @entity10116 @entity53 @entity134 @entity230
A chemiluminescence-based GH assay with 30- to 100-fold increased sensitivity recently disclosed combined basal and pulsatile GH secretion in @entity1 . However, how age, sex @entity134 hormones, and @entity28 singly and jointly influence the basal vs. pulsatile modes of GH release is not known. We used the foregoing assay (detection threshold, 0.002-0.005 microgram/L) and high sensitivity and specificity (> or = 90% each) deconvolution analysis to quantitate basal and pulsatile GH secretion from 24-h serum GH concentration profiles in 26 healthy lean and obese @entity1 , whose ages spanned 18-63 yr and whose percentage body fat ranged from 12-47%. Concentrations of serum @entity442 ( @entity442 ), @entity10116 ( @entity10116 ), and @entity2301 were related to specific measures of basal or pulsatile GH release. We observed that mean (24-h) serum GH concentrations embraced a 140-fold range from 0.013-1.8 micrograms/L and were related negatively to age (r = -0.50; P < 0.01), percentage body fat (r = -0.620; P < 0.01), and their interaction (r = -0.610; P < 0.01). In contrast, @entity251 was a robustly positive statistical determinant of mean serum GH values (r = 0.628; P = 0.0006). Stepwise multivariate regression analysis disclosed that percentage body fat alone and jointly with the serum @entity251 concentration controlled, respectively, 38% and 50% of the total variability in GH levels (P = 0.0013 and P = 0.0008). As assessed by deconvolution analysis, GH secretory burst mass was negatively related to percentage body fat (r = -0.621; P < 0.01) and positively to serum @entity251 (r = 0.529; P = 0.0054). The calculated half-life of GH correlated positively with serum @entity53 (r = 0.447; P = 0.032), and negatively with percentage body fat (r = -0.437; P = 0.048). Basal GH secretion rates were negatively related to serum @entity53 (r = -0.485; P = 0.016). In contrast, GH secretory burst frequency and duration were unrelated to age, percentage body fat, or sex @entity230 . The fraction of total GH secreted in bursts was negatively correlated with the body mass index (r = -0.540; P < 0.01). Serum @entity442 concentrations were positively related to total pulsatile GH secretion (r = 0.690; P = 0.0011) and negatively to age (r = -0.597; P = 0.007) and percentage body fat (r = -0.611; P = 0.009).(ABSTRACT TRUNCATED AT 400 WORDS)
