Pituitary and Intro Endocrine

Question 1

What are the 3 broad classifications of endocrine disease?

Answer 1

1. Impaired synthesis or release
2. Abnormal Interaction (hormone & target)
3. Abnormal response (by target)

OR

hyper / hypo / mass lesions

Question 2

What’s the normal size and weight of pituitary gland?

Answer 2

1 cm and about 5 gm pumpkin shaped organ

Question 3

What is this? And how is it sectioned?

Answer 3

normal pituitary

3 sections: adeno, neuro, intermediate

Question 4

What makes up the adenohypophysis component of the pituitary gland? (the cell type and the hormone associated)

Answer 4

80% of gland, from Rathke’s pouch (oral ectoderm); five cell types

1. Somatotrophs (GH),
2. Lactotrophs (PRL) {both Acidophilic – red}
3. Thyrotrophs (TSH),
4. Corticotrophs (ACTH & MSH),
5. Gondaotrophs (LH & FSH) {all Basophilic – blue}

Question 5

What makes up the neurohypophysis component of the pituitary gland? (the cell type and the hormone associated)

Answer 5

An extension of CNS, contains Pituicytes (modified glia), secretion is from Herring Bodies (Oxytocin & ADH, which are made in Hypothalamus but released here)

Question 6

Where are ADH and Oxytocin released?

Answer 6

at neurohypophysis from hypothalamus via hypothalamohypophyseal tract

Question 7

Where does the superior hypophyseal artery brings blood?

Answer 7

to Primary Plexus, which connects to the Secondary Plexus via the Hypophyseal Portal Veins (this whole connection brings blood and releaseing hormones to the adenohypophysis)

Question 8

Where does inferior hypophyseal a. provides blood?

Answer 8

to the neurohypohysis; from there, both sides flow to the systemic circuit

Question 9

List and rank by frequency the 4 main causes of hyperpituitarism.

Answer 9

1. adenoma in the anterior lobe
2. hyperplasia and carcinoma of anterior lobe
3. extra-pituitary tumor secretion (secretes trophic hormones)
4. hypothalamic disorders (excess releasing hormones)

Question 10

List and rank by frequency the 4 main causes of hypopituitarism

Answer 10

1. ischemic injury
2. surgery or radiation
3. inflammatory reaction
4. non-functional adenoma encroaching on normal tissue

Question 11

How does pituatary adenoma lead to hypopituitarism?

Answer 11

the adenoma grows and compresses good tissue leading to reduced or loss of function

Question 12

What’s the frequency of incidental pituitary adenomas at autopsy?

Answer 12

25% of routine autopsies

Question 13

What’s the percentage of intracranial neoplasms that are pituitary adenomas?

Answer 13

10% of intracranial neoplasms

Question 14

What’s the difference in size between microadenoma vs macroadenoma?

Answer 14

micro <1cm; macro > 1cm

Question 15

Are pituitary adenomas normally monoclonal or polyclonal?

Answer 15

monoclonal

Question 16

What are the different functions of pituitary adenomas?

Answer 16

non-functional; monohormonal; plurihormonal (esp. GH &PRL together)

Question 17

List and rank by frequency the types of pituitary adenoma.

Answer 17

1. prolactinoma (most common - 20-30%)
2. GH cell (2nd most common)
3. Null cell (20%; nonfunctional)
4. ACTH cell (10-15%)
5. Plurihormonals other than GH/PRL (10%)
6. Gonadotroph cell (5%)
7. GH/PRL cell (5%)
8. TSH cell (1%)

Question 18

What microscopically distinguishes a pituitary adenoma from non-neoplastic anterior pituitary parenchyma?

Answer 18

cellular monomorphism and lack of significant reticulin network

Question 19

What’s the classic visual field defect associated with mass lesions in the sella turcica?

Answer 19

bitemporal hemionopsia (lose both temporal fields)

Question 20

What’s clinically seen in patients with pituitary adenomas?

Answer 20

increased hormone secretion (type specific) or mass effect (includes: visual defects, increased ICP, hypopituitarism, hemorrhage associated with pituitary apoplexy, etc)

Question 21

What are 4 consequences of hyper-prolactinemia?

Answer 21

amenorrhea, galactorrhea, loss of libido, infertility (~hypo LH & FSH)

Question 22

What can potentially disrupt normal prolactin regulation?

Answer 22

1. damage to dopaminergic neurons in hypothalamus
2. damage to pituitary stalk
3. DA inhibitory drugs that may lead to hyperprolactinemia

Question 23

What is associated with aromegaly?

Answer 23

due to increased GH following closure of growth plates

have increased facial structures, hands, feet, viscera, and soft tissues

Question 24

What is associated with gigantism?

Answer 24

due to increased GH before closure of growth plates

increased growth in long bones and overall body size, with disproportionately long arms and legs

Question 25

What’s the pathophysiology of Nelson Syndrome?

Answer 25

disease of hypothalamo-pituitary adrenal axis

development of pituitary adenoma due to lack of negative feedback by corticosteroids on a pre-existing ACTH microadenoma

may occur following dual removal of adrenals associated with Cushing’s Syndrome - technically it was Cushing’s disease

Question 26

What’s a null cell adenoma?

Answer 26

A hormone negative tumor - it does not function and has no specific hormonal predilection in a true example

Most of the ones today are silent gonadotrophic adenomas

Question 27

Why do patients with null cell adenomas typically present with mass effects?

Answer 27

since there are no hormonal symptoms, the tumors go undetected until large enough to cause mass effect

Question 28

What’s the relative frequency and typical functional status of pituitary carcinomas?

Answer 28

quite rare and normally nonfunctional

varies in differentiations (may cause hyperpituitary); evidence of metastasis is usu. diagnostic (as in parathyroid adenocarcinoma)

Question 29

What’s the functional reserve of anterior pituitary?

Answer 29

75% - bc of the large degree of redundancy, it can handle fairly major disruptions

Question 30

What are some causes of hypopituitarism?

Answer 30

ischemic necrosis, surgery, inflammation, tumor or other mass lesions, pituitary apoplexy, Rathke cleft cyst, empty sella syndrome, genetic defects (rare), defects in releasing hormone deficiency

Question 31

What’s Sheehan Syndrome?

Answer 31

associated with necrosis following delivery

pregnancy related physiological expansion is NOT associated with increase blood supply, so during delivery, obstetric hemorrhage leads to DECREASE blood volume and possibly shock

pituitary susceptible to infarct - MOST COMMON cuase of hypopituitarism

Question 32

What are 5 signs or symptoms of hypopituitarism.

Answer 32

Depends on the hormone that is reduced.

1. GH - in children -> pituitary drawfism or just small stature
2. GnRH -> LH & FSH - amenorrhea, infertility, decresed libido, impotence
3. TSH & ACTH - lead to hypothyroid and hypoadrenal respectively
4. PRL - lack of normal lactation
5. MSH - lack of normal melanocyte stimulation -> hypopigmentation

Question 33

What are 2 products of posterior pituitary?

Answer 33

ADH/Vasopression (H₂O balance and vasoconstriction)

Oxytocin (uterine contraction, milk ejection)

Question 34

Define diabetes insipidus.

Answer 34

polyuria due to ADH deficiency - kidney’s inability to reabsorb water (if lack of production [central] or lack of response [nephrogenic])

symptoms: dilute urine, hypernatremia, and increased osmolarity -> leads to polydipsia

Question 35

What are some causes of diabetes insipidus?

Answer 35

head trauma, inflammation, tumor, and surgery

Question 36

Define syndrome of inappropriate antidiuretic hormone (SIADH).

Answer 36

Excess secretion of ADH leads to excess volume retention & hyponatremia; leads to Cerebral Edema, increased Total Body Water, BUT normal BV & NO peripheral edema!

Question 37

What are the 4 most common causes of SIADH?

Answer 37

1. Ectopic ADH by malignant neoplasm (esp small cell of lung)
2. non-neoplastic lung disease
3. local injury to hypothalamus or neurohypophysia
4. per wiki: head injury, cancer, infection, drugs