Isolated growth hormone deficiency in children and adolescents

Although it is difficult to reach international agreement on the definition of growth hormone deficiency (GHD) in children and adolescents, great effo rts to do so have been made during the last two decades. A somewhat limited definition of GHD is: a combination of auxological, clinical, biochemical and metabolic abnormalities caused by lack or insufficiency of GH secretion that results in a decrease in the production of GH-dependent hormones and growth factors. Its aetiology is very complex. Therefore, specific studies must be performed during different periods of childhood (neonatal, prepuber tal and pubertal periods). Auxological parameters, particularly growth velo city (GV), are still considered the best clinical measures for analysing hu man growth. The spectacular advances in our understanding of molecular biol ogy during the past twenty years have allowed, and will continue to allow, a more and more precise diagnosis of the molecular anomalies of human growt h. This will, in turn, allow changes caused by genetic lesions to be more e fficiently distinguished from those due to nutritional, organic, tumoural, psychological or traumatic causes. Our knowledge of the molecular bases of undergrowth due to a deficiency in GH has developed as a result of the loca lisation and characterisation of human genes which code for proteins implic ated in the hormonal regulation of growth. These genes include pituitary GH (GIII), pituitary transcription factor 1 (Pit-1), the prophet of Pit-1 (PR OP-1), the pituitary transcription factor LHX3, the transcription factor HE SX1 and the GH-releasing hormone receptor (GHRHr). In addition, magnetic re sonance imaging is the best available imaging method for the evaluation of size and structure of the pituitary and the parasellar region.