Question

1. Anybody want a peanut? Andre the Giant had gigantism AND acromegaly from a somatotrophic pituitary adenoma. What does a somatotrophic pituitary adenoma do to growth hormone secretion (1 pts)? What specifically occurs on a cellular/physiological level to cause the symptoms of heightened stature, large hands, large feet, large jaw, large internal organs, and increased blood sugar (4 pts)? Which symptom is not associated with acromegaly (1 pts)? What other disorder often occurs alongside gigantism and acromegaly due to the symptom of increased blood sugar (1pts)? What are the two possible courses of treatment for these conditions (2 pts)? (FYI Andre refused treatment to continue his career in wrestling). 1 pts for essay formatting, grammar, spelling.

Answer 1

Somatotrophic cells are cells in the anterior pitutary that produces growth hormones in response to somatostatin (growth hormone releasing hormone). An adenoma (a non-cancerous benign tumor) in these somatotrophic cells is called somatotrophic pitutary adenoma. The common outcomes of this type of adenoma are gigantism and acromegaly. Both of these disorders are caused by an excessive action of IGF-1 (insulin like growth factor-1) but, differs in the fact that gigantism occurs while the epiphyseal growth plates are open during childhood, whereas acromegaly occurs in adults where the epiphyseal growth plates are closed. A somatotrophic adenoma causes an increase in the production of insulin like growth factor(IGF-1) in the liver. When the level are IGF-1 raises acromegaly occurs.

Increase in growth hormones are the causes of large hands, feet and jaw. Chronic expoosure to hypersecretion of growth hormone and IGF-1 leads to soft tissue swelling of heart, kidney, colon and tongue causing the increase in size of these organs. Increase in IGF-1 increases insulin sensitivity. Increase in the level of growth hormones stimulates gluconeogenesis and lipolysis which causes increases blood sugar (hyperglycemia).

Heightened stature is not associated with acromegaly. The abnormal linear growth of the body is associated with gigantism.

Increased levels of free fatty acids and hyperglycemia caused by gluconeogenis and lipolysis leads to hepatic and peripheral insulin resistance, with compensatory hyperinsulinemia.
The two possible course of treatment for acromegaly are surgery, radiation and medication. Surgical removal of the adenoma reduces the further abnormal growth. Facial features begin to improve within few days. The changes in soft tissues are the first to notice after the removal of the tumor.

Drug therapy includes administration of different types of drugs such as growth hormone receptor antagonist, somatostain analogs, and dopamine agonists. The growth hormone receptor antagonist prevents the hormone released from the tumor to function by inhibiting its binding to the receptor. The only drug to perform this function is pegvisomat. It is available under the brand name Somavert. It is administered as a subcutaneous injection.

The somatostatin analogs inhibit the release of hormone from the tumor and also to supress the size of the tumor. The common drugs used as somatostatin analogs are 1. octreotide which is available in two forms: subcutaneous injection thrice a day and a long lasting form which is injected intrmuscularly once a month. 2. lanreotide which is administered subcutaneously once a month.

If surgery is not an option and if the tumor does not respond to medication, radiotherapy might be needed.