ChemPath: Pituitary and adrenals Flashcards

1
Q

What are the hypothalamic hormones

A

GHRH

GnRH

TRH

Dopamine

CRH

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2
Q

Action of GHRH

Action of GnRH/LHRH

Action of Thyrotrophin releasing hormone

Action of dopamine

Action of Corticotrophin releasing hormone

A

Stimulates GH

Stimulates LH/FSH

Stimulates TSH and Prolactin

Inhibits prolactin

Stimulates adrenocorticotropic hormone

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3
Q

Indications for Combined pituitary function test

A

Assess all components of anterior pituitary function

particularly in pituitary tumours or following tumour treatment

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4
Q

Contraindications to Combined pituitary function test

A

Ischaemic heart disease

Epilepsy

Untreated hypothyroidism (impairs the GH and cortisol response)

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5
Q

Side effects Combined pituitary function test

A

Sweating, palpitations, LOC (Adr levels rise if glucose stays low)

Rarely: convulsions with hypoglycaemia

Neuroglycopenia (aggression, irritable, coma when glucose <1.5nM). Give 20% dextrose

Pts should be warned that with the TRH injection, may experience transient metallic taste in mouth, flushing and nausea

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6
Q

3 components Combined pituitary function test

A

Stress i.e. hypoglycaemia (glucose <2.2) fasting and give insulin (0.15ml/kg)to cause hypoglycaemia

Give TRH 200mcg

Give LHRH 100 mcg

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7
Q

Normal cortisol/ glucose/ GH response in CPFT

Abnormal response

A

Cortisol: reaches 550nmol/l

GH: >10 IU/L

glucose <2.2 (if not give mroe insulin)

Failure to increase cortisol and GH

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8
Q

Tx pituitary failure

A
  1. Urgent hydrocortisone (or pred?)
  2. Also replace thyroxine, oestrogen, GH

If prolactinoma cause: give cabergoline/bromocriptine (DA agonist)

If non-functioning pit. tumour, do above and surgery if tumour large enough and consider bromo/caber. Also Humphreys test for bitemporal hemianopia and MRI/CT Ix

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9
Q

Tx prolactinoma

A

Dopamine agonist: cabergoline, bromocriptine

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10
Q

pituitary failure and prolactin > 6000

A

prolactinoma

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11
Q

Sx pituitary failure

commonest cause
Ix

other causes

Tx

A

galactorrhoea
amenorrhoea

macroadenoma (>1cm)
CPFT Humphreys test for bitemporal hemianopia, MRI/CT

prolactinoma (if pit failure + prolactin >6000)

Hydrocortisone, GH, thyroxine, oestrogen (+/- surgery and bromocriptine)

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12
Q

Increased GH, commonly due to GH secreting pituitary adenoma

increase in IGF-1

A

Acromegaly

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13
Q

Sx Acromegaly

A

rare
40-50 y/o
associated with MEN-1
sweating, headache, visual disturbance, carpal tunnel, galactorrhoea, amenorrhoea

osteoarthritis, high BP, DM, psychosis

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14
Q

Ix Acromegaly

A

OGTT (cannot suppress GH

IGF-1 (will be high)

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15
Q

Mx Acromegaly

A

Transphenoidal hypophysectomy +/- pituitary radiotherapy

Cabergoline (to lower GH)

Octreotide (somatostatin analogue)

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16
Q

posterior pituitary hormones

A

antidiuretic hormone

oxytocin

17
Q

Zones of adrenals and what they make

A
Zona Glomerulosa - aldosterone
Zona Fasciculata - cortisol (thicker layer)
Zona Reticularis - androgens
Medulla- adrenalline 
Capsule (surrounds everything)
18
Q

Difference between rt and lt adrenal vein

A

Right adrenal vein drains straight into IVC

left adrenal vein -> renal vein -> IVC (cannulate this to check hormones)

19
Q
31 year old presents with profound tiredness. Acutely unwell a few days. Vomiting.
Results
Na: 125, K=6.5 U=10 
Glucose = 2.9 mM
FT4 <5nM TSH >50 mU/l

Diagnosis?

Why low glucose/ high K?

A

primary hypothyroidism

low t4, high TSH

Low glucose - lack cortisol
High K - low aldosterone

–> ADDISON’S DISEASE

20
Q

What is Schmidt syndrome

A

primary hypothyroidism + addison’s disease

auto-antibodies to thyroid and adrenal

21
Q

Test for Addison’s

A

Synacthen test (give ACTH)

  • Measure 9am cortisol + give 250micrograms synthetic ACTH by IM injection
  • Check cortisol at 30 and 60 minutes
  • Addison’s = <10nM cortisol, and baseline ACTH will be >100 ng/dl
  • Repeat test - if cortisol still very low then = addison’s disease
22
Q

Sx of Addison

A

Low BP and dizzy

losing Na

23
Q

Cause of Addison’s

A

Autoimmune, TB

24
Q

Tx Addison’s

A
IV fluids (normal saline)
Hydrocortisone
25
Q

Test for Cushings

A

see if you can suppress cortisol

low dose dexamethasone suppression test

26
Q

Test for acromegaly

A

Glucose tolerance test

GH will remain high in acromegaly

27
Q

32 y/o presents with HTN and adrenal mass. What are three possible DDx?

A

Phaeochromocytoma - very rare (adrenal medullary tumour secreting adrenaline) - blasts of HTN

Conn’s syndrome (adrenal glomerulosa tumour) - constant HTN and low K, small tumour

Cushing’s syndrome (adrenal fasciculata tumour - secreted cortisol)

28
Q

Sx Phaeochromocytoma

A

severe episodic HTN, arrhythmias (VF), stroke and death

MEDICAL EMERGENCY

29
Q

Phaeochromocytoma

associated with…

A

MEN II
VHL
NF1

30
Q

Tx Phaeochromocytoma

A

urgent alpha blockade with doxazosin/phenoxybenzamine with saline ( so pt stable)
Then add beta blockade (so BP drops)
Then surgery to remove tumour

31
Q

33 y/o hypertensive man presented with following results :
Na 147, K 2.8, U 4.0, Gluc 4.9 mM
Plasma aldosterone raised (low K, high Na)
Plasma renin suppressed

Diagnosis?

A

Primary hyperaldosteronism
Conn’s syndrome (Conn’s adenoma)
- hypertension (as Aldosterone makes you retain Na and lose K in urine) and renin suppression at the JGA

NB secondary hyperaldosteronism is when renin is HIGH

32
Q

Tx Conn’s

A

Spironolactone

Remove tumour

33
Q
A 34-year-old obese woman with type 2 diabetes, presented with hypertension, bruising and the following results.
Na: 146 mM, K 2.9, U 4.0, Gluc 14.0
Plasma aldosterone suppressed (<75)
Plasma renin: suppressed.
Diagnosis?
A

Cushing’s syndrome

34
Q

Difference between Cushing’s syndrome and Cushing’s disease.

How to determine cause

A

Cushing’s syndrome = any cause of features of high cortisol (moon face, buffalo hump, thin skin, stretch marks, osteoporosis, diabetes). Causes can be adrenal mass, pituitary (causing bilateral adrenal hyperplasia, lung Ca (causing ectopic ACTH release)

Cushing’s disease = pituitary tumour CAUSING Cushing’s syndrome

Check if taking steroids. Then do pituitary MRI and sampling from pituitary (IPSS)

35
Q

Test for Cushings

A

Dex suppression test

midnight cortisol (will be high)

36
Q

Causes Cushing’s

A

Oral steroids (commonest)
Pituitary dependent Cushing’s disease
Ectopic ACTH
Adrenal adenoma