Endocrine - Online MedEd - Anterior pituitary

Question 1

Posterior pituitary is a continuation of which structure

Answer 1

Thalamus

-Hypothalamus has neurons that go into the posterior pituitary

Question 2

ACTH causes secretion of…

Answer 2

Cortisol

for BP control

Question 3

ACTH pathway

Answer 3

Hypo –> CRH –> Ant pit –> ACTH –> target organ –> adrenal –> hormone is cortisol (respond to stress/increase blood glucose)

Question 4

TSH pathway

Answer 4

Hypo –> TRH –> TSH –> thyroid –> release T4 –> metabolic activity

Question 5

GH pathway

Answer 5

Hypo –> GHrH –> GH –> liver –> insulin-like growth factor 1 –> causes growth

Question 6

FSH/LH path

Answer 6

GnRH –> FSH/LH –> reproductive organs –> testosterone and estrogen –> reproduction

Question 7

What is the negative feedback loop?

Answer 7

Original hormones from pituitary and hypothalamus get produced (default)
Distal hormone turns off proximal hormones

Question 8

Prolactinoma - what is it?

Answer 8

Prolactin secreting tumour
Not a cancer
Benign!

Question 9

Presentation - prolactinoma

Answer 9

Women - amenorrhea, galactorrhea - present with microadenomas (unlike men were tumours present bigger, this is because women will notice these symptoms). As the tumours are small there is no visual field deficit

Men - don’t have breasts that produce milk, can’t notice amenorrhea and galactorrhea - symptoms are reduced libido, will get macro adenoma, may get bitemporal hemianopsia

Question 10

Where does the pituitary sit and what can it affect?

Answer 10

Optic chiasm

-Field cuts

Question 11

Diagnosis of prolactinoma

Answer 11

Check meds that might increase prolactin - like DA antagonists
TSH - hypothyroidism can induce prolactinoma
Check PRL level
Need MRI to look for tumour*

Question 12

Treatment of prolactinoma

Answer 12

Use dopamine agonists - cabergoline better than bromocriptine
Rarely will need surgery and radiation

Question 13

Prolactin and dopamine - what relationship?

Answer 13

Dopamine inhibits prolactin
So dopamine antagonists (such as antipsychotics) disinhibit inhibition on prolactin –> cause prolactinoma like symptoms, reason for noncompliance

Question 14

Prolactin and TRH relationship?

Answer 14

TRH stimulates prolactin

So in hypothyroid –> low T4, elevated TRH –> prolactinoma

Question 15

Prolactinoma - what labs/imaging

Answer 15

Measure TSH - if hypothyroid, will be high and treat with levothyroxine
If normal TSH, get prolactin level –> if elevated PRL, get MRI
MRI positive - prolactinoma –> use dopamine agonists

Question 16

Acromegaly - what is it?

Answer 16

Benign tumour
Growth hormone secreting
Can cause cancer cells to grow, other cells

Question 17

Acromegaly - presentation

Answer 17

Kids look different than adults

• Kids before closure of growth plates, cause long bones to grow - gigantism
• Adults after fusion of growth plates, all things that can grow, will! Hands, feet, face, visceral organs, will also get Diabetes (because GH causes glucose to rise)
• Hands don’t fit, hat resized

Question 18

What is the killer in acromegaly in adults?

Answer 18

Diastolic heart failure - LV hypertrophy is so bad!

Question 19

Acromegaly - diagnosis?

Answer 19

Check insulin-like growth factor 1
If elevated, do glucose suppression test
If glucose suppression test is positive, then get an MRI

Question 20

Only treatment for acromegaly

Answer 20

Surgery!

Can use octreotide/somatostatin (turns insulin like growth hormone to stasis)

Question 21

What does growth hormone tell the liver?

Answer 21

Make glucose - diabetes

Make insulin-like growth factor 1 - stimulate bones, and heart to grow

Question 22

What is the glucose suppression test?

Answer 22

If suppression test suppresses glucose, then not acromegaly

• Give someone an oral glucose load, what should happen is insulin should increase to lower glucose; other hormones should shut off
• Positive test, is when GH that should decrease, does not change!

Question 23

Regulation of insulin?

Answer 23

Epinephrine, growth hormone, cortisol

Insulin tries to bring down glucose

Question 24

Hypopituitarism - presentation

Answer 24

1) Sudden, acute, devastating - causes: infection, infarction, iatrogenic (i.e. take too many tumour during surgery) - catastrophic
2) Chronic, insidious - causes: autoimmune, deposition disease, slow growing tumour that gradually presses on stalk

Question 25

Loss of cortisol by adrenal removal can lead to catastrophic symptoms

Answer 25

Hypotensive

Tachycardic

Question 26

Loss of T4 presents with

Answer 26

Lethargy

Coma

Question 27

Diagnosis of hypo pit?

Answer 27

Assess levels of cortisol and T4 - random level

Question 28

Treatment of hypo pit?

Answer 28

Replace with hormones

Question 29

Recognize Sheehan’s

Answer 29

Pregnancy
Prolonged delivery
Blood loss
Infarct of pituitary
Get coma right after

Question 30

Recognize apoplexy

Answer 30

Large tumour recognized

Obtunded, nuchal rigidity, headache

Question 31

Patient will try to preserve in chronic hypo pit. What is the main hormones?

Answer 31

1) ACTH
2) TSH
3) GH less important - fatigue
4) FSH/LH - loss of libido/menstruation
* Very vague symptoms

Question 32

How to diagnose hypo pit that is chronic?

Answer 32

Because ACTH and TSH will be preserved
Test the GH by using an insulin stimulation test, can also do the vasopressin stimulation test
If these are positive, check MRI

Question 33

Insulin stimulation test - how does it work?

Answer 33

If give insulin, BG will fall
Epi, GH, and cortisol will be stimulated
Failure for GH to rise means a lack of these hormones

Question 34

Treatment of hypo pit that is chronic?

Answer 34

Replace hormones and fix the underlying disease and treat underlying disease

Question 35

Empty sella - what is it?

Answer 35

Ant pituitary sits next to post pituitary in sella
Empty sella still has pituitary but the sella is empty
Diagnosis made on MRI
Patient is asymptomatic because there is still pituitary!
Do nothing!