Pituitary and Thyroid

Question 1

Drugs affecting the thyroid

Answer 1

Iodine and potassium iodide

Liothyronine (T3) and Levothyroxine (T4) both treat hypothyroidism. Long half life. 1x per day dose.

Methimazole and propylthiouracil both tx hyperthyroidism. Inhibit production of T3 and T4, but no effect on T3 and T4 already stored. short half life. Multiple day dosing.

Question 2

Somatropin vs somatostatin

Answer 2

Stomatropin- Growth Hormone

Somatostatin- GHIH

Question 3

Gonadotropin

Answer 3

LH and FSH

Question 4

Gonadorelin

Answer 4

Gonadotropin releasing hormone (from the hypothalamus)
Must be released in pulse doses.
Continuous dose causes negative feedback.

Question 5

Synthetic compounds of GnRH

Answer 5

Leuprolide
Gonadorelin
Nafrelin

Question 6

Hypersecretion of GH/somatropin causes

Answer 6

Gigantism- proportional
Acromegaly- disproportional

Under secretion causes dwarfism.

Question 7

Prolactin secretion is inhibited by

Answer 7

dopamine

Question 8

Post pit

Answer 8

Extension of the hypothalamus. NOT a separate organ. 
Secretes vasopressin (ADH) and oxytocin. 

The vasopressin and oxytocin precursors are synthesized by hypothalamus and stored in the posterior pituitary. NOT regulated by releasing hormones.

Question 9

Can you give any pituitary hormones orally?

Answer 9

NO! Not ant or post. most are proteins/peptides

Question 10

Does the anterior pit synthesize its own hormones? what about posterior

Answer 10

Anterior- synthesizes own. Does not store.

Posterior- stores from hypothalamus and then releases.

Question 11

Signs of hypothyroidism

Answer 11

Brady, cold intolerance, mental and physical slowing.

Dx: elevated TSH
Tx: T3 or T4 (liothyronine T3, Levothyroxine T4)

Question 12

Signs of hyperthyroidism

Answer 12

Tachy, excess heat production, increased metabolism.
Dx: Decreased TSH.
Tx: Methimazole or propylthiouracil. Inhibits production of T3 and T4. or surgical removal. Pt may develop hypothyroidism after surgery.

Question 13

Drugs that induce the P450 system accelerate the metabolism of

Answer 13

Thyroid hormones. T3 and T4.

Question 14

6 hormones released by anterior pituitary

Answer 14

TSH 
LH 
FSH 
GH 
Prolactin 
ACTH

Question 15

5 hormones released by the hypothalamus

Answer 15

Thyroid releasing 
GnRH 
corticotropin releasing hormone 
GHRH
GHIH

*2 for GH, none for prolactin.

Question 16

Proteins and peptide hormones

Answer 16

Insulin, LH, oxytocin, angiotensin II

Question 17

GHIH does what

Answer 17

Suppresses GH and TSH release

Also inhibits release of insulin, glucagon, and gastrin.

Used to tx tumors that are reliant on GH

Question 18

How can GnRH be used to suppress gonadal hormones?

Answer 18

If released continuously. Can treat prostate cancer, endometriosis

Question 19

How are hormones of the posterior pituitary regulated?

Answer 19

Not regulated by releasing hormones. Released in response to specific physiological signs.

Question 20

When can oxytocin be used to induce labor

Answer 20

Only full term

Question 21

Vasopressin causes increased water reabsorption in the kidney (tx diabetes insipidus) and causes constriction of vascular smooth muscle.

What is a modified version that does not constrict vascular smooth muscle?

Answer 21

Desmopressin

Question 22

TSH release from ant pit results in

Answer 22

Uptake of iodide and synthesis of t3 and t4 –> released into the blood.

T3 and T4 are bound to plasma proteins upon release, (inactive) They must dissociate from protein before entering cell.

T4 is enzymatically changed to t3 by the cell. Regulates gene expression.

Question 23

Admin of T3 and T4/

Answer 23

Well absorbed after oral admin. Drugs that induce the p450 system accelerate metabolism of the thyroid hormones.

Question 24

How to treat thyroid storm (hyperthyroidism)

Answer 24

Beta blockers to stop sympathetic stimuluation
Same therapy, but more aggressive.

dose of iodide inhibits the production of hormone. but this only lasts a few days.