Endocrine - Online MedEd - Anterior pituitary Flashcards Preview

Endocrine > Endocrine - Online MedEd - Anterior pituitary > Flashcards

Flashcards in Endocrine - Online MedEd - Anterior pituitary Deck (35):
1

Posterior pituitary is a continuation of which structure

Thalamus
-Hypothalamus has neurons that go into the posterior pituitary

2

ACTH causes secretion of...

Cortisol
for BP control

3

ACTH pathway

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

4

TSH pathway

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

5

GH pathway

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

6

FSH/LH path

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

7

What is the negative feedback loop?

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

8

Prolactinoma - what is it?

Prolactin secreting tumour
Not a cancer
Benign!

9

Presentation - prolactinoma

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

10

Where does the pituitary sit and what can it affect?

Optic chiasm
-Field cuts

11

Diagnosis of prolactinoma

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

12

Treatment of prolactinoma

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

13

Prolactin and dopamine - what relationship?

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

14

Prolactin and TRH relationship?

TRH stimulates prolactin
So in hypothyroid --> low T4, elevated TRH --> prolactinoma

15

Prolactinoma - what labs/imaging

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

16

Acromegaly - what is it?

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

17

Acromegaly - presentation

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

18

What is the killer in acromegaly in adults?

Diastolic heart failure - LV hypertrophy is so bad!

19

Acromegaly - diagnosis?

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

20

Only treatment for acromegaly

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

21

What does growth hormone tell the liver?

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

22

What is the glucose suppression test?

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!

23

Regulation of insulin?

Epinephrine, growth hormone, cortisol
Insulin tries to bring down glucose

24

Hypopituitarism - presentation

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

25

Loss of cortisol by adrenal removal can lead to catastrophic symptoms

Hypotensive
Tachycardic

26

Loss of T4 presents with

Lethargy
Coma

27

Diagnosis of hypo pit?

Assess levels of cortisol and T4 - random level

28

Treatment of hypo pit?

Replace with hormones

29

Recognize Sheehan's

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

30

Recognize apoplexy

Large tumour recognized
Obtunded, nuchal rigidity, headache

31

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

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

32

How to diagnose hypo pit that is chronic?

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

33

Insulin stimulation test - how does it work?

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

34

Treatment of hypo pit that is chronic?

Replace hormones and fix the underlying disease and treat underlying disease

35

Empty sella - what is it?

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!