ChemPath: Pituitary and adrenals Flashcards
What are the hypothalamic hormones
GHRH
GnRH
TRH
Dopamine
CRH
Action of GHRH
Action of GnRH/LHRH
Action of Thyrotrophin releasing hormone
Action of dopamine
Action of Corticotrophin releasing hormone
Stimulates GH
Stimulates LH/FSH
Stimulates TSH and Prolactin
Inhibits prolactin
Stimulates adrenocorticotropic hormone
Indications for Combined pituitary function test
Assess all components of anterior pituitary function
particularly in pituitary tumours or following tumour treatment
Contraindications to Combined pituitary function test
Ischaemic heart disease
Epilepsy
Untreated hypothyroidism (impairs the GH and cortisol response)
Side effects Combined pituitary function test
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
3 components Combined pituitary function test
Stress i.e. hypoglycaemia (glucose <2.2) fasting and give insulin (0.15ml/kg)to cause hypoglycaemia
Give TRH 200mcg
Give LHRH 100 mcg
Normal cortisol/ glucose/ GH response in CPFT
Abnormal response
Cortisol: reaches 550nmol/l
GH: >10 IU/L
glucose <2.2 (if not give mroe insulin)
Failure to increase cortisol and GH
Tx pituitary failure
- Urgent hydrocortisone (or pred?)
- 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
Tx prolactinoma
Dopamine agonist: cabergoline, bromocriptine
pituitary failure and prolactin > 6000
prolactinoma
Sx pituitary failure
commonest cause
Ix
other causes
Tx
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)
Increased GH, commonly due to GH secreting pituitary adenoma
increase in IGF-1
Acromegaly
Sx Acromegaly
rare
40-50 y/o
associated with MEN-1
sweating, headache, visual disturbance, carpal tunnel, galactorrhoea, amenorrhoea
osteoarthritis, high BP, DM, psychosis
Ix Acromegaly
OGTT (cannot suppress GH
IGF-1 (will be high)
Mx Acromegaly
Transphenoidal hypophysectomy +/- pituitary radiotherapy
Cabergoline (to lower GH)
Octreotide (somatostatin analogue)
posterior pituitary hormones
antidiuretic hormone
oxytocin
Zones of adrenals and what they make
Zona Glomerulosa - aldosterone Zona Fasciculata - cortisol (thicker layer) Zona Reticularis - androgens Medulla- adrenalline Capsule (surrounds everything)
Difference between rt and lt adrenal vein
Right adrenal vein drains straight into IVC
left adrenal vein -> renal vein -> IVC (cannulate this to check hormones)
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?
primary hypothyroidism
low t4, high TSH
Low glucose - lack cortisol
High K - low aldosterone
–> ADDISON’S DISEASE
What is Schmidt syndrome
primary hypothyroidism + addison’s disease
auto-antibodies to thyroid and adrenal
Test for Addison’s
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
Sx of Addison
Low BP and dizzy
losing Na
Cause of Addison’s
Autoimmune, TB
Tx Addison’s
IV fluids (normal saline) Hydrocortisone
Test for Cushings
see if you can suppress cortisol
low dose dexamethasone suppression test
Test for acromegaly
Glucose tolerance test
GH will remain high in acromegaly
32 y/o presents with HTN and adrenal mass. What are three possible DDx?
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)
Sx Phaeochromocytoma
severe episodic HTN, arrhythmias (VF), stroke and death
MEDICAL EMERGENCY
Phaeochromocytoma
associated with…
MEN II
VHL
NF1
Tx Phaeochromocytoma
urgent alpha blockade with doxazosin/phenoxybenzamine with saline ( so pt stable)
Then add beta blockade (so BP drops)
Then surgery to remove tumour
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?
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
Tx Conn’s
Spironolactone
Remove tumour
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?
Cushing’s syndrome
Difference between Cushing’s syndrome and Cushing’s disease.
How to determine cause
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)
Test for Cushings
Dex suppression test
midnight cortisol (will be high)
Causes Cushing’s
Oral steroids (commonest)
Pituitary dependent Cushing’s disease
Ectopic ACTH
Adrenal adenoma
