End 2 - Pituitary

Question 1

From where does the anterior lobe of the pituitary develop?

Answer 1

Forms from Rathke’s pouch (ectodermal diverticulum).

Question 2

From where does the posterior lobe develop?

Answer 2

Form from invagination of the hypothalamus (neuroectoderm).

Question 3

What does ADH do?

Answer 3

Decreased urine output. Vascular smooth muscle constriction.

Question 4

What are 2 stimulators of ADH?

Answer 4

Nicotine and Opiates.

Question 5

What are 3 inhibitors of ADH?

Answer 5

Ethanol. Atrial natriuretic factor. Decreased osmolarity.

Question 6

What does Oxytocin do?

Answer 6

Milk ejection (breast). Uterine contraction.

Question 7

What does FSH do? What is the upstream regulatory hormone?

Answer 7

In women, FSH causes follicular development. In men, acts on Sertoli cells to mature sperm (spermatogenesis). The upstream regulatory hormone is Gonadotropin releasing hormone (GnRH), and must be pulsatile.

Question 8

What does LH do? What is the upstream regulatory hormone?

Answer 8

In men, it causes testosterone production by stimulating Leydig cells. In women it acts on theca-lutean cells to help produce estrogen and progesterone production. The upstream regulatory hormone is GnRH and its release must be pulsatile.

Question 9

What substance inhibits FSH?

Answer 9

Inhibin.

Question 10

What substance inhibits LH?

Answer 10

Progesterone and testosterone.

Question 11

What four hormones all have a common alpha-subunit?

Answer 11

LH. FSH. TSH. hCG.

Question 12

What does ACTH do? What is the upstream regulatory hormone?

Answer 12

Stimulates the adrenal cortex to produce and release hormones like cortisol. The upstream hormone is corticotropin releasing hormone (CRH). Cortisol itself is a negative feedback on the release of ACTH.

Question 13

What does Melanin releasing hormone do?

Answer 13

MSH, it stimulates the release of melanin and involved in sexual arousal.

Question 14

How is ACTH and MSH related?

Answer 14

ACTH is synthesized as part of a large precursor called proopiomelanocrotin (POMC), which also contains the sequence for other hormonal peptides, includiing the lipotropins, melanocyte-stimulating horomones (MSH) and beta-endorphins.

Question 15

Why do we see skin hyperpigmentation in primary adrenal insufficiency?

Answer 15

In this disease, cortisol is low so the hypothalamus releases CRH, which in turn makes POMC, where ACTH is derived from; ACTH stimulates more cortisol. However, the POMC is also the precursor for MSH. Therefore, increased POMC leads to increased MSH as well, giving the hyperpigmentation.

Question 16

What does TSH do? What is the upstream hormone regulator?

Answer 16

Makes Thyroid hormone production and secretion, T3, and T4. Regulated upstream by Thyroid releasing Hormone (TRH).

Question 17

What does GH do? What is the upstream hormone regulator?

Answer 17

It stimulates growth, decrease glucose uptake, increase protein synthesis and organ size and lean body mass. The upstream regulating hormone is Growth hormone releasing hormone (GHRH) and growth hormone inhibiting hormone (somatostatin).

Question 18

What is the downstream hormone for Growth hormone?

Answer 18

Insuli-like growth factor-1 (IGF-1).

Question 19

What conditions stimulate GH release?

Answer 19

Exercise. Sleep. Puberty. Hypoglycemia. Estrogen. Stress. Endogenous opiates.

Question 20

What conditions inhibit GH release?

Answer 20

IGF-1. Obesity. Pregnancy. Hyperglycemia.

Question 21

What does prolactin do? What upstream hormone regulates it?

Answer 21

Causes milk production and secretion. Inhibits ovulation by inhibiting GnRH. It is stimulated by TRH. It is inhibited by dopamine.

Question 22

What are the causes of hyperprolactinemia?

Answer 22

Pregnancy/nipple stimulation. Stress (physical/psychological). Prolactinoma (associated w/ bitemporal hemianopsia). Dopamine antagonists: antipsychotics (haloperidol, risperidione), domperidone, metoclopramide, methyldopa (Technically a dopa analogue that inhibits dopa decarboxylase).

Question 23

What would be the symptoms of hyperprolactinemia in a Male?

Answer 23

Hypogonadism (low test) which causes decreased libido, impotence, infertility (low sperm count), gynecomastia, rarely galactorrhea.

Question 24

What would be the symptoms of hyperprolactinemia in a premenopausal female?

Answer 24

Hypogonadism which leads to infertility, oligo/amenorrhea, rarely galactorrea.

Question 25

What would be the symptoms of hyperprolactinemia in a postmenopausal female?

Answer 25

None since already hypogonadal.

Question 26

Why does hyperprolactinemia causes hypogonadism?

Answer 26

Because it inhibits GnRH, which means low LH and FSH.

Question 27

Why can a prolactinoma cause bitemporal hemianopsia?

Answer 27

It can because of its location: the tumor can impinge on the optic chiasm.

Question 28

What is the treatment for prolactinoma?

Answer 28

Bromocriptine and Cabergoline. Surgical intervention.

Question 29

How do we diagnose acromegaly or gigantism?

Answer 29

Check IGF-1 because GH is released in a pulsatile manner. To confirm the high IGF-1, you do the oral glucose tolerance test and check the GH instead of the glucose (GH should go down unless it is a tumor, which GH will stay the same).

Question 30

What does somatostatin do?

Answer 30

In the CNS, PNS, and peripheral organs somatostatin decreases endocrine and exocrine secretion, reduces splanchnic blood flow, reduces gastrointestinal motility and gallbladder contraction, and inhibits secretion of most gastrointestinal hormones.

Question 31

When do we use somatostatin?

Answer 31

Pituitary excess: acromegaly, thyrotropinoma, ACTH-secreting tumors. GI endocrine excess: Zollinger-Ellison syndrome, carcinoid syndrome, VIPoma (AKA pancreatic cholera), glucagonoma, insulinoma. Certain diarrheal disease. Need to reduce splachnic circulation: portal hypertension (bleeding varices), bleeding peptic ulcers.

Question 32

What is Sheehan syndrome?

Answer 32

Occurs after the delivery of a baby if the mom had massive postpartum hemorrhage that caused underperfusion of the pituitary, which causes necrosis. this leads hypopituitarism. Causes agalactorrhea, amenorrhea, hypothyroidism, hyponatremia.

Question 33

A patient's MRI revels replacement of tissue in the sella turcica w/ CSF. What is the most likely clinical presentation?

Answer 33

"Empty Sella" Usually enough residual pituitary cells to cause no symptoms, but can cause symptoms of pituitary hormone deficiency.

Question 34

What are 5 clinical symptoms of acromegaly?

Answer 34

Large hands and feet. Coarse facial features. Increased spacing of teeth. Deep voice. Impaired glucose tolerance or diabetes.

Question 35

RFF: Inability to breastfeed, amenorrhea, cold intolerance.

Answer 35

Sheehan syndrome.

Question 36

RFF: Infertility, galactorrhea, and bitemporal hemianopsia.

Answer 36

Prolactinoma.