pk3

Question 1

What are the consequences of growth hormone excess after puberty?

Answer 1

Increased periosteal bone growth, increased organ size, increased hand and foot size, enlargement of the tongue, coarsening of facial features, insulin resistance and glucose intolerance.

Question 2

How is growth hormone excess treated?

Answer 2

Treated with somatostatin analogues (e.g., octreotide).

These drugs inhibit growth hormone secretion by the anterior pituitary, similar to endogenous somatostatin.

Question 3

What are the causes of undersecretion of pituitary hormones?

Answer 3

1. Nonsecreting pituitary adenoma or craniopharyngioma.
2. Sheehan syndrome: Ischemic infarct of the pituitary following postpartum bleeding.
3. Empty sella syndrome: Atrophy or compression of the pituitary, often idiopathic.
4. Pituitary apoplexy: Sudden hemorrhage of the pituitary gland, often with an existing adenoma.
5. Brain injury or radiation.

Question 4

What is Sheehan syndrome, and how does it present?

Answer 4

1. Ischemic infarct of the pituitary following postpartum bleeding.
2. Pregnancy-induced pituitary growth increases susceptibility to hypoperfusion.
3. Presents with:
   
   • Failure to lactate.
   • Absent menstruation.
   • Cold intolerance.

Question 5

What is empty sella syndrome, and who is most commonly affected?

Answer 5

1. Atrophy or compression of the pituitary gland (located in the sella turcica).
2. Often idiopathic and common in obese females.
3. Associated with idiopathic intracranial hypertension.

Question 6

What is pituitary apoplexy, and how does it present?

Answer 6

1. Sudden hemorrhage of the pituitary gland, often in the presence of an existing pituitary adenoma.
2. Presents with:
   
   • Sudden onset severe headache.
   • Visual impairment (e.g., bitemporal hemianopia, diplopia due to CN III palsy).
   • Features of hypopituitarism.

Question 7

How is pituitary hormone undersecretion treated?

Answer 7

1. Hormone replacement therapy, including:
   
   • Corticosteroids.
   • Thyroxine.
   • Sex steroids.
   • Human growth hormone.

Question 8

Where is prolactin mainly secreted from?

Answer 8

Prolactin is mainly secreted by the anterior pituitary.

Question 9

What are the functions of prolactin?

Answer 9

1. Stimulates milk production in the breast.
2. Inhibits ovulation in females and spermatogenesis in males by inhibiting GnRH synthesis and release.

Question 10

How is prolactin secretion regulated?

Answer 10

1. Tonic inhibition by dopamine from the tuberoinfundibular pathway of the hypothalamus.
2. Prolactin inhibits its own secretion by increasing dopamine synthesis and secretion from the hypothalamus.
3. TRH increases prolactin secretion (e.g., in primary or secondary hypothyroidism).

Question 11

How is prolactin structurally related to growth hormone?

Answer 11

Prolactin is structurally homologous to growth hormone.

Question 12

What is associated with excessive amounts of prolactin?

Answer 12

Excessive prolactin is associated with decreased libido.