ESPE Abstracts

Background: GH is secreted in a pulsatile manner. The resulting GH peaks are known to be associated with growth, whereas the trough levels between the peaks are thought to be associated with metabolism in different tissues. GH trough levels were identified as a metabolically active signal in rats in the 1980th leading to differences in fat patterning with central obesity. Obese children are known to have low bone mass and bone mass is reduced in short children.

Objective and hypotheses: To evaluate the impact of GH trough levels and waist circumference on bone metabolism in short prepubertal children. Our hypothesis was that the trough levels are associated with bone metabolism.

Method: The study population consisted of 137 short prepubertal children (age range, 3–11 years; 91 boys, 46 girls) who participated in a longitudinal, prospective, multicenter study. Children had either normal or reduced levels of GH secretion. Data from baseline examinations were analyzed.

Results: The GH baseline/GHmax ratio (correlation loading in PCA, r=0.724), lipotrotein(a) (r=0.383) and waist/hip ratio (r=0.705) formed a cluster and correlated inversely with bone mineral content (BMC–SDS) (r −0.732). This indicates a negative influence of high GH baseline levels on bone metabolism and thus bone metabolic GH resistance.

Conclusion: This is the first time that trough levels of GH have been identified as a potentially metabolically active signal in man. The association of the ratio of minimum to maximum GH secretion with bone mass indicates a partial metabolic GH resistance in bone tissue. We suggest GH trough levels being a metabolically active signal on bone tissue in man.