Hypothalamic/Pituitary

Question 1

What is GHRH used for?

Answer 1

Recombinant form used to stimulate growth hormone secretion in people with short stature

Question 2

What is somatostatin used for?

Answer 2

Inhibits release of glucagon, insulin, gastrin, TSH, and growth hormone; an example is Octreotide

Question 3

What is GnRH used for?

Answer 3

Stimulates release of FSH and LH; when given pulsatile simulates physiological action

Question 4

What is CRH used for?

Answer 4

Stimulates release of ACTH from anterior pituitary through activation of cAMP

Question 5

What is TRH used for?

Answer 5

Stimulates release of thyrotropin from anterior pituitary, and prolactin

Question 6

What does dopamine do in the pituitary pathway?

Answer 6

Inhibits prolactin release

Question 7

What time of day, and stage of human development do growth hormone and prolactin peak?

Answer 7

At night (around midnight) and puberty

Question 8

What happens to blood glucose when IGF is increased?

Answer 8

Blood glucose decreases

Question 9

What happens when too much growth hormone is released?

Answer 9

In childhood you have gigantism, in adulthood you have acromegaly

Question 10

What drug is used for growth hormone deficiency that is responsive to growth hormone treatment?

Answer 10

Somatropin

Question 11

What drug treats growth hormone receptor mutation, or abnormal signaling that is not responsive to growth hormone treatment?

Answer 11

Mescasermin (IGF-1 agonist)

Question 12

Where does somatropin act, and what are it’s effects?

Answer 12

Acts through growth hormone receptors to increase IGF-1; restores normal growth and metabolic defects in GH deficient patients

Question 13

What are symptoms of somatropin toxicity and what is it contraindicated in?

Answer 13

TOX: Malignancy, papilledema, visual disturbances, GH replacement therapy can cause diabetes mellitus, scoliosis, edema, etc.

CONTRA: Active malignancy

Question 14

Other than GH deficiency, what are other uses of somatropin?

Answer 14

1. Prader-Willi (decrease obesity, growth, and carbohydrate intolerance)
2. Turner Syndrome (treated w/ growth factor and gonadal steroid)
3. Idiopathic short stature
4. Chronic renal failure
5. AIDS related wasting
6. Malabsorption due to short bowel syndrome.

Question 15

What is the mechanism of action, and effects of Mescasermin?

Answer 15

Recombinant form of IGF-1 that stimulates the IGF-1 receptors; restores normal growth in patients with a receptor mutation of GH or IGF-1 deficiency who are resistant to GH

Question 16

What are some Mescasermin toxicities?

Answer 16

Hypoglycemia, intracranial hypertension, increased liver enzymes

Question 17

What drug is used in gigantism and acromegaly patients?

Answer 17

Somatostatin

Question 18

What is the mechanism and effects of Octreotide?

Answer 18

Agonist of somatostatin receptors, inhibiting GH production, and to a lesser extent glucagon, insulin, and gastrin

Question 19

What are some clinical applications of Octreotide?

Answer 19

Acromegaly, carcinoid syndrome, acute bleeding from esophageal varices, diabetic diarrhea, localization of GI serotonin tumor

Question 20

What are some toxicities of Octreotide?

Answer 20

GI disturbances, gallstones, bradycardia, and other cardiac conductibility disturbances.

Question 21

What is similar to Octreotide and used in long-acting therapy?

Answer 21

Lanreotide

Question 22

What is the mechanism of action and some effects of Pegvisomant?

Answer 22

Blocks GH receptors; ameliorates effects of excess GH production in acromegaly patients.

Question 23

What is the toxicity for Pegvisomant?

Answer 23

Elevated liver enzymes

Question 24

What is the difference in V1 and V2 for the ADH receptor?

Answer 24

V1 - smooth muscle - vasoconstriction

V2 - kidney - aquaporin - water resorption

Question 25

What is the mechanism and effects of Atosiban?

Answer 25

Blocks oxytocin receptors causing decreased uterine contractions; tocolysis for preterm labor.

Question 26

What are some toxicities of Atosiban?

Answer 26

Concern about rates of increased infant deaths. NOTE: This is the first IV drug administration, the GH ones were subcutaneous

Question 27

What does vasopressin (ADH) do, and what is it used for?

Answer 27

Activates V2 to increase water permeability and resorption, concentrating urine. Used in Central Diabetes Insipidus Activates V1 to cause vasoconstriction. Used in variceal or controlled bleeding.

Question 28

What are side effects of vasopressin (ADH)?

Answer 28

Hypertension and bradycardia

Question 29

What is the mechanism of action of Desmopressin, and some effects?

Answer 29

Activates vasopressin (V2 > V1) receptors; so agonist, acts in kidney to decrease excretion of water, acts on extra-renal V2 receptors to increase Factor VIII & Von Willebrand

Question 30

What are the clinical applications, route of administration, and toxicities of Desmopressin?

Answer 30

1. Pituitary diabetes inspidius, hemophilia A & Von Willebrand disease, nocturnal enuresis. 2. Oral, IV, SC, or nasal 3. GI disturbances, headache, hyponatremia, allergic rxns

Question 31

What is the water deprivation test, and how is it interpreted?

Answer 31

1. Diagnose between central and nephrogenic diabetes insipidus. 2. Normal person the urine after water deprivation and desmopressin is >750 mOsmol/kg; diabetes insipidus is <300 mOsmol/kg. Central if increases after AVP, nephro if not changed by AVP

Question 32

What is SIADH and the treatment for it?

Answer 32

Inappropriate secretion of ADH, usually caused by tumor or injury in lung/brain, characterized by low blood sodium Tx: Restrict water intake, hypertonic saline, Conivaptan, Demeclocycline, and Lithium

Question 33

What are some important side effects of lithium?

Answer 33

Nephrogenic diabetes insipidus, and hypothyroidism

Question 34

What is the mechanism of action, how it's administered and some effects of Conivaptan?

Answer 34

Antagonist of V1a and V2 receptors, which increases renal excretion of water. Used for hyponatremia patients in hospitalized SIADH. Administered via IV

Question 35

What are symptoms of microadenoma of the pituitary and what is it treated with?

Answer 35

Amenorrhea, galactorrhea, treated with bromocriptine and cabergoline. More common in females.

Question 36

What are the symptoms of macroadenoma of the pituitary and what is it treated with?

Answer 36

Visual field defect, treated with surgery (trans-sphenoid approach) and radiation. More common in males.