Endocrine Flashcards
Endocrine + Adrenals
How to manage Addisonion crisis?
IV 0.9% Saline
IV hydrocortisone
Cushings syndrome - anatomy of the adrenal gland?
Fasiculata tumour secreting cortisol
How to manage Addison’s disease?
Hydrocortisone + sick-day rules
Fludrocortisone
What is Conn’s syndrome - adrenal anatomy?
Glomerulosa secreting aldosterone
Phaeochromocytoma genetic links? (3)
- MEN2
- Von Hippel Lindau Syndrome
- Neurofibromatosis type 1
Signs and symptoms seen in Congenital adrenal hyperplasia?
21-OH deficiency :
- Salt losing crisis (due to low aldosterone produced)
- Virilisation (due to high testosterone / androgen produced instead)
Why may you have
Hyperplastic adrenal glands?
Cushings disease or ectopic ACTH
What are the most common causes of Addison’s disease in the UK
**Autoimmune (UK most common) **
TB (worldwide most common)
Metastasis
Haemorrhage (Waterhouse-Friedrichson Syndrome)
Iatrogenic
Adrenal histology:
Wasted adrenal glands likely to be caused by which conditions?
Addison’s disease or long term steroid treatment
How to treat Ectopic ACTH causing cushings syndrome? (3)
Ketoconazole
Metyrapone
Mifepristone
How to confirm the cause of cushings?
IPSS : inferior petrosal sinus sampling:
Catheter into jugular vein, distinguishes pituitary dependent cushings from ectopic ACTH by measuring ACTH in veins coming from pituitary
What is a Paeochromocytoma - adrenal anatomy?
Medulla tumour secreting adrenaline
How to test for phaeochromocytoma?
How to treat this medical emergency?
urinary catecholamines will be high (due to medulla secreting access adrenaline)
- Immediate Alpha blockade with phenoxybenzamine
- then add a beta blockade
- then surgery
How to test for addisons?
Short synacthen test:
Measure cortisol and ACTH at the start
- give 250ug ACTH, IM
Check cortisol levels at 30 and 60 minutes
The cortisol will be very low <10nM (not making any cortisol in response to exogenous ACTH challenge)
ACTH will be >100g/dl
What might this be?
33 yr old, HTN
Urea and electrolytes:
Na = 147
K = 2.8
U = 4.0
Glucose = 4.0mM
Plasma aldosterone raised
Plasma renin suppressed
Conns syndrome (primary hyperaldosteronism)
- too much aldosterone = HTN and suppression of renin at JGA
Addison’s disease investigation
9am cortisol to confirm low cortisol
to confirm : short synACTHen test
–> blood sample to measure cortisol before test
–> shorth ACTH synthetic injected to stimulate glands to produce cortisol
–> blood samples after 30 and 60 mins to measure cortisol levels
What is Cushing’s syndrome?
High cortisol which can have exogenous cause (glucocorticoid medications) or endogeneous cause (cushings disease, adrenal adenoma, ectopic ACTH)
What are the most common causes of Addison’s disease?
Autoimmune (UK most common)
TB (worldwide most common)
Metastasis
Haemorrhage (Waterhouse-Friedrichson Syndrome)
Iatrogenic
31yo, profound fatigue, acutely unwell for a few days, vomiting
Test results:
Na = 125
K = 6.5
U = 10
FT4 = <5nM
TSH = >50mU/L
What is this?
- Primary hypothyroidism
- Unusual U&Es –> Addisons
(mineralcorticoid and glucocorticoid deficiency)
If you have both Addisons + hypothyroidism =
Schmidt’s syndrome aka polyglandular autoimmune syndrome type II
What is Cushing’s disease?
Pituitary cause of cushings syndrome (pituitary adenoma excess ACTH)
What does this patient have?
Obese women, T2DM, HTN, Bruising
Na - 146
K - 2.9
Aldosterone - <75
Renin - Low
Urea - 4.0
Glucose - 14
Cushings syndrome (low potassium and high glucose with cortisol pushing the hypertension)
Low potassium : excess cortisol can act like aldosterone by binding to mineralcorticoid receptors in kidney = stimulate sodium retention at expence of potassium excretion. Also in turn increases blood pressure.
What deficiency drives Congenital adrenal hyperplasia?
21-OH deficiency
Why is the high dose dexamethasone suppression test NOT DONE anymore?
because 85% are pituitary-dependant without the test and so doing a high-dose test is less accurate (false +ve = 20%) than guessing and so it is not useful
Equally, pituitary MRIs with gadolinium enhancement is not that useful but can be definitive
What are the most common causes of Addison’s disease worldwide
Autoimmune (UK most common)
TB (worldwide most common)
Metastasis
Haemorrhage (Waterhouse-Friedrichson Syndrome)
Iatrogenic
How to screen for Cushing’s syndrome?
Look for hypercortisolism:
11pm salivary cortisol
–> If low : Rules out cushings
–> if high : Suspicion
Low dose dexamethasone suppression test:
The patient takes 1 mg of dexamethasone at 11 pm, and cortisol is measured at 9 am the next morning.
–> Normal suppression : no cushings, may be peusdo-cushings
–> Abnormal suppression : Cushings syndrome (cushings disease / steroids / ectopic / adrenal adenoma
== Do IPSS to confirm cause
How to treat Cushings syndrome from adrenal mass?
Adrenalectomy +/- steroid replacement
- beware of Nelson’s syndrome:
Leads to pituitary enlargement to compensate releasing loads of ACTH causing alot of hyperpigmentation.
What is Addison’s disease?
Not enough cortisol + aldosterone:
phaeochromocytoma emergency presentation?
Severe hypertension, arrythmias and death
Because of adrenaline tumour
What is nelson’s syndrome?
Adrenalectomy +/- steroid replacement
beware of Nelson’s syndrome:
Leads to pituitary enlargement to compensate for adrenalectomy by releasing loads of ACTH causing alot of hyperpigmentation.
What is shmidth syndrome?
polyglandular autoummune syndrome type 2:
primary hypothyroidism with Addisons
(Low T3/T4 and Low cortisol/aldosterone = high TSH + high ACTH)
What prolactin levels hint towards hyperprolactinaemia?
6000 + = prolactinoma
If 600 - 6000 = non functioning pituitary adenoma
How to diagnose hyperprolactinaemia?
Combine pituitary function test (triple test):
Give insulin + TRH + GnRH
normal response would be:
- cortisol 500+
- GH 10 +
- LH 10 +
useful to diagnose hypopituitarism that can occur due to prolactinoma compressing normal tissue
How to manage prolactinoma?
Cabergoline / Bromocriptine (DA agonist)
How to assess acromegaly?
OGTT 75mg with measurement of GH:
GH 2+ acromegaly
GH <2 normal
May also see increase in prolactin 600-6000
instead of OGTT, how can you monitor acromegaly after diagnosis?
IGF1 levels
How to manage acromegaly?
Ocreotide (somatostatin analogue)
Cabergoline (for prolactin)
surgery = transsphenoidal surgery 1st line
What are the anterior pituitary hormones?
ADH
Oxytocin
Microadenoma vs macroadenoma of pituitary?
micro = <10
macro = >10, aggressive
What are contraindications to using the combined pituitary function test?
Ischaemia heart disease
Epilepsy
Untreated hypothyroidism (Will impair GH and cortisol response)
How to give the CPFT (combined pituitary function test)
Patient to fast overnight
Insulin 0.15/kg, TRH 200mg, LHRH 100mcg IV
Measure bloods, 0 min, 60 min, 90 min, 120min
How to interpret the CPFT?
Insulin part:
hypogyclaemia caused should stimulate stress response increasing cortisol 500+ and GH to increase about 6
TRH part:
TRH should increase TSH to 5+ and prolactin to also increase
GnRH part:
Should stimulate LH 10+ and FSH 2+
What can cause excess ADH?
Lung : lung paraneoplasias (SCLC)
Brain : Traumatic brain injury, tumours, meningitis
Iatrogenic : SSRI, amitriptyline, carbamazepine, PPIs
