Growth Hormone Excess

Overview
  • Excessive secretion of Growth Hormone (GH) can be caused by a variety etiologies; however, most cases are due to pituitary adenomas of somatotroph cells. Because GH is critical for linear bone growth, the clinical consequences of GH excess are different depending on the age of onset. GH excess prior to puberty results in the syndrome of Gigantism whereas excess after pubescence results in the syndrome of Acromegaly.
Gigantism
  • The presence of excess GH in children prior to pubescence results in excessive growth of long bones as closure of the epiphyses has not occurred. This results in an abnormally tall stature and excessively long extremities such as the arms and legs. Importantly, if the GH hypersecretion is not corrected, post-pubescent GH excess will yield symptomology of acromegaly, described below.
Acromegaly
  • The clinical syndrome of acromegaly occurs in those with GH excess during adult life following pubescent closure of the epiphyses. The symptomology of acromegaly involves the slow development of a characteristic set of physical features. Because of its slow evolution and protean manifestation, acromegaly is classically difficult to diagnose. Overgrowth of a variety of bones results in a broadening of the face, protrusion of the jaw, and enlargement of the hands and feet. Expansion of the soft tissue may result in coarse facial feature and enlargement of the nose. Patients with acromegaly display enlargement of a number of visceral organs, especially in the heart. This ventricular hypertrophy can contribute to Left Heart Failure or arrhythmias. Finally, patients with excess GH frequently tend to display significant peripheral insulin resistance, leading to hyperglycemia that often evolves into Type II Diabetes Mellitus.