Hypothalamic & Pituitary Disorders (Schmidt)

Question 1

The anterior pituitary is composed of tissue of glandular origin and contains what two types of cells? What sort of tissue is the posterior pituitary composed of?

Answer 1

acidophils and basophils (and chromophobes); posterior pit has neural tissue.

Question 2

descriptive term used for, as an example, headaches that result from a growing tumor that presses against the pituitary stalk, gland, or other brain regions

Answer 2

tumor mass effects

Question 3

generally benign tumor of epithelial origin derived from glandular tissue that may be functional (hormone excess) or nonfunctional (see below - no clinical manifestations of hormone excess but may cause mass effects)

Answer 3

adenoma

*nonfunctional tumors are usually diagnosed later because there is no clinical evidence of their existence until they get big enough to cause problems

*note the homogeneity and loss of collagen in pituitary adenoma

Question 4

very rare malignant tumors of the pituitary gland

Answer 4

carcinoma

Question 5

tumors of the posterior lobe are referred to as ______ and are very rare, consisiting of poorly characterized glial cells

Answer 5

astrocytomas

Question 6

Which of the following statements regarding abnormal secretion of ADH is FALSE?

A. Hypersecretion of ADH may result in hypertension, swelling of the brain, convulsions and coma

B. Ectopic secretion of ADH by malignant tumors may occur in locations that don’t normally contribute to ADH secretion (ie, small cell carcinoma of the lungs

C. Central diabetes insipidus is characterized by decreased secretion of ADH from the pituitary gland, and is most often idiopathic though may be caused by trauma

D. Nephrogenic diabetes insipidus can be classified as either acquired (most common) or congenital and is treated with desmopressin

E. Hyposecretion of ADH results in polyuria, polydipsia and nocturia

Answer 6

D. Nephrogenic diabetes insipidus should be treated with thiazide diuretics to allow increased excretion of Na+ and water, which reduces serum osmalarity. Central diabetes insipidus is treated with desmopressin.

he says it’s really important to know the difference between the two forms of diabetes insipidus

Question 7

what would happen to secretion of prolactin if the hypothalamic were severed?

Answer 7

it would go up - because dopamine, produced in the hypothalamus, would not be able to reach the anterior lobe of the pituitary gland, where it tonically inhibits prolactin

Question 8

_____ is the lack of secretion of one or more pituitary hormones whereas _____ is characterized by a signficant reduction in secretion of all anterior pituitary hormones.

Answer 8

hypopituitarism; panhypopituitarism

Question 9

most common cause of elevated prolactin levels (hyperprolactinemia)

Answer 9

prolactinomas; make up about 25-30% of all benign pituitary tumors

Question 10

what is one of the major feedback effects of high prolactin levels?

Answer 10

it feedback inhibits LH and FSH –> infertility, galactorrhea, decreased libido, hypogonadism

Question 11

the treatment of choice for hyperprolactinemia (lowers prolactin in 70-100% of patients)

Answer 11

bromocryptine mesylate (dopamine agonist)

Question 12

hyposecretion of growth hormone results in all of the following except:

A. pituitary dwarfism

B. low IGF-1 levels

C. lack of insulin production

D. slow muscle development

E. delayed bone maturation

Answer 12

C. It leads to lack of insulin antagonism, in other words, there is too much insulin and this results in hypoglycemia

*treatment for hyposecretion of growth hormone is recombinant hGH

Question 13

deficiency of this hormone is rare in adults, and is characterized by reduced bone mass, increased abdominal adipose tissue, and increased psychological problems (memory, depression)

Answer 13

growth hormone

Question 14

pediatric patients presenting with very tall stature due to elevated IFG-1 and pituitary diabetes may have what condition?

Answer 14

pituitary gigantism

Question 15

how would pituitary gigantism, caused by the hypersecretion of growth hormone in children that have not yet reached puberty, be treated?

Answer 15

somatostatin analogues that inhibit growth hormone secretion (ie, octreotide)

Also, surgery to remove hormone-secreting adenoma or radiation therapy.

Question 16

what causes most cases of acromegaly?

Answer 16

benign adenoma (95% of cases)

Question 17

what is the pharmacologic treatment for hypersecretion of growth hormone, that works by blocking the GH receptor?

Answer 17

pegvisomant

*it is a growth hormone receptor antagonist, engineered from hGH, that only binds to one site of the receptor (A side)

Question 18

precocious puberty is defined as prior to ___ years old in girls and ____ years old in boys

Answer 18

8; 9

*most cases are idiopathic (90%) but some may be caused by a hypothalamic tumor, hypersecreting GNRH

Question 19

benign, non-neoplastic nodules present at birth caused by development abnormality in the hypothalamus (ie, improper cell migration) and resulting in pulsatile hypersecretion of GnRH

Answer 19

hamartoma - leads to precocious puberty

Question 20

Which of the following is NOT a symptom of hypersecretion of GnRH from the hypothalamus?

A. early menarche in girls

B. breast development (precocious puberty)

C. increased libido in young boys

D. exaggerated adult height

Answer 20

D. Hypersecretion leads to short adult height, due to the effects of estrogen on epihyseal fusion

Question 21

In the 50% of cases of hypersecretion of GnRH that need to be treated (that lead to precocious puberty), what is the pharmacological approach?

Answer 21

GnRH agonists - seems counterintuitve, but the reason it works is that it is the continuous stimulation of the pituitary gonadotrophs which causes a decrease in LH and FSH secretion

Question 22

name 3 GnRH agonists (synthetic derivatives) used to treat hypersecretion of GnRH

Answer 22

anastrozole, histrelin, leuprolide

Question 23

A 37 year-old male has complained to his wife that his wedding ring no longer fits over his finger and that his size 9 shoes are very uncomfortable because they now seem to be too small for his feet. His wife is also concerned that her husband’s facial appearance has changed over the past year and wonders why his nose seems to look so “puffy”. After seeing an endocrinologist the man is started on a new medication. In order for this drug to be effective in reducing some of his signs and symptoms, it should mediate which of the following intracellular events with regard to the hormone receptor which mediates the effects causing these symptoms and signs?

A. inhibit receptor auto-phosphorylation

B. inhibit nuclear translocation of the receptor

C. block receptor dimerization

D. block receptor-mediated activation of its coupled G protein

Answer 23

C. This is the mechanism of action of Pegvisomant, which is used to treat acromegaly.

Question 24

The parents of a 5 year-old boy are concerned about some changes in their son’s physical appearance as well as his behavior. They’ve noticed coarse black hair growing on his arms and legs and believe that this should not occur until he is much older. The boy’s pre-school teacher is very concerned because this young boy becomes very aggressive with very young girls in his group. The most appropriate medication for this child would be which of the following?

A. anastrozole

B. somatostatin analogue

C. bromocriptine mesylate

D. pegvisomant

Answer 24

A. Anastrozole is a GnRH receptor agonist used to inhibit the pulsatile secretion of GnRH from the hypothalamus to ultimately decrease LH and FSH levels and decrease testosterone production.