#2- Pituitary

Question 1

This one of the earliest signs of pituitary tumor or abnormal growth

Answer 1

Bitemporal hemianopia
Aka loss of aspects of vision
Compression of optic chiasm—> peripheral vision loss

Question 2

The hypothalamus regulates:

Answer 2

Appetite, sleep, activity of the ANS, and pituitary hormone secretions

Question 3

Posterior pituitary hormones

Answer 3

ADH (vasopressin) and Oxytocin

Question 4

Anterior pituitary hormones

Answer 4

TSH, ACTH, LH, FSH, prolactin, GH

Question 5

TRH axis

Answer 5

TRH in hypothalamus–> TSH via thyrotroph cells of ant. Pit—> thyroid gland to release T3 and T4 for metabolism regulation & calcitonin from parathyroid glands for minor role in blood calcium levels

Question 6

GHRH axis

Answer 6

GHRH via hypothalamus—> GH/somatotropins via somatotroph cells—> insulin like growth factors (IGFs) from liver for cell growth and cessation of apoptosis

Question 7

Most frequent pediatric intracranial neoplasm

Answer 7

Craniopharyngioma

- arises from squamos cell nests in primitive Rathke pouch

Question 8

Why is the pituitary gland known as the “master gland”

Answer 8

It influences the hormonal secretions of other endocrine glands via releasing trophic hormones

Question 9

CRH axis

Answer 9

CRH via hypothalamus—> ACTH via corticotroph cells of the anterior pit—> glucorticoids (CHO metabolism and stress response) and mineralcorticoids (weakly: aldosterone to regulate BP and water reabsorption) via adrenal glands

Question 10

GTRH axis

Answer 10

GTRH via hypothalamus—> FSH and LH via gonadotroph cells of ant. Pit—> ovaries and testes which function in growth of ovaries and testes, output of sex hormones, regulating menstrual cycle in women, and male androgen release

• LH: testosterone and progesterone
• FH: estradiol and inhibin

Question 11

Role of somatostatin:

Answer 11

Inhibitory hormone via hypothalamus which inhibits TSH and GH/somatotropins via somatotroph cells in the ant. Pit

Question 12

Role of dopamine:

Answer 12

Inhibitory hormone via hypothalamus which inhibits prolactin stimulation by TRH via lactotroph cells in the anterior pituitary

Question 13

Vasopressin Role

Answer 13

Posterior pituitary hormone

Stimulates kidneys to reabsorb water; regulates BP

Question 14

Oxytocin role

Answer 14

Posterior pituitary hormone

Stimulates breasts and uterus for contraction of uterus and prostaglandin release

Question 15

Prolactin inhibition and fx:

Answer 15

• dopamine
• drugs mimicking dopamine

Fx: stimulates milk production in breast tissue

Question 16

Prolactin stimulation:

Answer 16

• TRH
• estrogen
• nipple sucking

Question 17

Role of somatostatin released by the hypothalamus:

Answer 17

• inhibits TSH

- inhibits GH

Question 18

Two inhibitory enzymes released by the hypothalamus:

Answer 18

Somatostatin

Dopamine

Question 19

Tumor effects depend on

Answer 19

1- Hormones: amount and type
2- Tumor: size and location
3- Patient: age

Question 20

Functioning tumors release which 2 hormones:

Answer 20

GH or prolactin

Question 21

MC adenoma

Answer 21

Microadenoma

- benign but may be functional

Question 22

Microadenoma size and hormone release

Answer 22

<1 cm/10 mm and prolactin

Question 23

Macroadenoma size and hormone release

Answer 23

> 10 mm and GH

Question 24

Benign adenoma more common in adults

Answer 24

Meningioma

- always non-functional

Question 25

Prolactinoma s/s in women

Answer 25

MC microadenomas - menstrual irregularities; menopause; pain w/ sex; vaginal dryness; and osteoporosis - 30-80% w/ galactorrhea: may be B/L or unilateral

Question 26

S/s Prolactinoma in men:

Answer 26

Decreased libido, erectile dysfunction and infertility (gynecomastia is rare)

Question 27

These symptoms arise as adenomas increase in size

Answer 27

Compression s/s aka visual field deficits

Question 28

Hyperprolactinemia differential dx:

Answer 28

``` 1- pregnancy (MC and #1 to think of) 2- drugs that inhibit dopamine 3- ESRD/cirrhosis 4- endocrine disorders: (aka too much TRH being release) hypothyroidism or adrenal insufficiency 5- hypothalamic or pituitary pathology ```

Question 29

W/u for prolactinoma:

Answer 29

Check TSH and prolactin levels (pregnancy test if female) 1st: MRI w/ thin cuts/contrast 2nd: CT w/ contrast if sella abnormal

Question 30

Treatment for prolactinoma:

Answer 30

1- most microprolactinomas do not progress—> so mild s/s? Then yearly MRI and w&w 2- Meds: Bromocriptine—> dopamine agonist and tumor shrinks 3- Surgery: Transphenoidal pituitary adenectomy

Question 31

Excessive GH in adults leads to

Answer 31

Acromegaly

Question 32

excessive GH in children leads to

Answer 32

Gigantism

Question 33

MC cause of excessive GH

Answer 33

Functional pituitary adenoma | - 70% of acromegalics have a macroadenoma; 1/3 of functional adenomas secrete GH

Question 34

Anterior lobe of hypothalamus secretes hormones via

Answer 34

Pituitary Portal circulation

Question 35

Posterior lobe of hypothalamus secretes hormones via

Answer 35

Directly by a neural network in the pituitary stalk to the posterior lobe