Growth Hormone Excess and Other Conditions of Overgrowth

Tall stature is characterized by a height that is more than 2 SDs above the mean for age and sex, and may or may not be associated with increased growth velocity. The most common cause of tall stature is familial tall stature, which is not associated with increased growth velocity. This diagnosis should be considered after a detailed history, physical examination, and selected laboratory evaluation have ruled out syndromic and nonsyndromic causes of tall stature. Growth hormone (GH) excess is associated with increased growth velocity and tall stature when it manifests before epiphyseal fusion. Besides tall stature, clinical features include coarse facial features, prognathism, arthralgias, and skeletal deformities. IGF-1 levels and the nadir GH level after glucose administration help confirm the diagnosis. Subsequent radiologic investigations and visual field testing provide information regarding the location, size, and invasiveness of the somatotroph adenoma and help plan further management. Surgery is the first line of therapy. However, multimodal therapy (surgical, medical, and radiologic) may be necessary to control tumor size and GH excess. Somatostatin analogs are used when surgery is not successful in removing the entire tumor and sometimes preoperatively to reduce tumor size and decrease IGF-1 levels, which may improve surgical outcomes. Dopamine agonists and the growth hormone receptor blocker, pegvisomant, are other options for medical therapy. Radiation therapy may be necessary to control tumor size and IGF-1 levels if surgery and medical therapy are not effective. Long-term complications related to GH excess and treatment should be monitored and adequately addressed. Glucose intolerance, hypertension, sleep apnea, cardiovascular complications, and vertebral fractures can be seen in patients with prolonged GH excess.