Growth Hormone Neurosecretory Dysfunction as a Clinical Entity

Abstract

Growth hormone neurosecretory dysfunction (GHND) is part of a spectrum of disorders of growth hormone (GH) secretion and action that range from classic GH deficiency (GHD) to partial GH insensitivity. GHND patients develop circulating levels of GH above an arbitrary level (frequently 10 ng/mL) in response to pharmacological stimuli, but have low spontaneous endogenous production of GH. However, GHND is difficult if not impossible to diagnose in the individual patient because of the inherent variability of the assessment of GH endogenous secretion and peak GH response to provocative testing. The lack of a clear linkage between long term response to GH treatment for short stature and any auxologic or biochemical parameters make the selection of short patients for treatment difficult. It is necessary to use a combination of careful auxological and biochemical assessments of short children for the appropriate selection of patients for GH treatment. Indirect ways of assessing endogenous GH metabolism such as insulin-like growth factor I (IGF-I), IGF binding protein-3 (IGFBP-3), and GH binding protein (GHBP), are more reproducible than direct GH testing, and may be useful in the definition of subtle disorders of GH secretion and action in individual patients. The diagnostic categorization of patients with short stature as GH/IGF axis dysfunction may prove to be useful.