Growth Hormone Deficiency
- Deficient secretion of Growth Hormone (GH) can be caused by a variety etiologies. Because GH is critical for linear bone growth, the clinical consequences of GH excess are different depending on the age of onset (Review: Growth Hormone Physiology).
- GH deficiency in children is often due to inherited mutations in a variety of genes which render peripheral body tissues insensitive to GH. In some cases, mutations may affect the anterior pituitary receptor for hypothalamic GHRH, resulting in deficient GH secretion by an otherwise normal pituitary.
- Acquired GH deficiency in adults is typically due to progressive destruction of the pituitary due to expansion of a neoplasm such as a pituitary adenoma. GH-secreting somatotrophs typically possess the least physiological reserve; thus, as the neoplasm expands GH deficiency is observed first followed by deficiencies of other anterior pituitary hormones.
- GH deficiency beginning in children prior to puberty will present as abnormally short stature along with a small penis and episodic of hypoglycemia.
- GH deficiency in adulthood develops slowly and thus may be challenging to diagnose. GH-deficient adults may complain of lethargy and decreased energy. Derangements of adiposity often arise with decreased total lean body mass, increased adipose tissue, and hyperlipidemia. Finally chronic reductions in GH may result in reduced bone density manifesting as an increased risk of bone fractures.