Chempath 15: Adrenal Disease Flashcards
What are the 3 zones of the adrenal cortex ?
Zona glomerulosa
Zona Fasciculata
Zona Reticularis
In which zone of the adrenal cortex is aldosterone produced ?
Zona Glomerulosa
In which zone of the adrenal cortex is cortisol produced ?
Zona fasciculata
In which zone of the adrenal cortex are androgens such as DHEA produced ?
Zona reticularis
DHEA (dehydroepiandosterone) is a precursor to male and female sex hormones including oestrogen and testosterone
Where is adrenaline produced ?
Adrenal Medulla
List 2 potential causes of hyperplastic Adrenal glands ?
Cushing’s disease Ectopic ACTH (e.g lung tumour)
Where does the Right adrenal gland drain into ?
Inferior vena cava (IVC)
Where does the left adrenal gland drain into ?
Left renal vein
What is schmidt’s syndrome ?
A syndrome of co-existing hypothyroidism and Addison’s disease due to autoantibodies against both the thyroid and the adrenals
Hyponatraemia + hyperkalaemia (mineralocorticoid deficiency)
Hypoglycaemia (glucocorticoid (cortisol) deficiency)
low T4 high TSH (Primary hypoparathyroidism)
Aka polyglandular autoimmune syndrome type II
Which test is used to diagnose Addison’s disease ?
Short synACTHen test
Explain how the short synACTHen test works and what results you would expect in Addison’s disease ?
1)- measure initial cortisol +ACTH
2)- Administer synthetic ACTH 250mcg by IM injection
3)- check cortisol at 30 and 60 mins
In normal people cortisol should be able get to >550 nM within 30 mins
In Addison’s disease Cortisol does increase after synthetic ACTH and stays <10nM
Which test is used to diagnose phaeochromocytoma?
Urine catecholamines - high = phaeochromocytoma
What is a phaeochromocytoma ?
An adrenal medullary tumour that secretes adrenaline causing hypertension, arrhythmias, sweating, impending sense of doom
List 3 genetic conditions in which phaeochromocytoma is seen?
MEN2
Von Hippel Lindau syndrome
Neurofibromatosis type 1
List 3 features of MEN2a?
Parathyroid tumours
Medullary thyroid cancer
Phaeochromocytoma
List 4 features of Von Hippel Lindau syndrome ?
Phaeochromocytoma
Renal cell carcinoma
Renal cysts
Retinal/CNS haemangioblastomas
List up to 6 features of Neurofibromatosis type 1
Peripheral and spinal neurofibromas Cafe au lait spots Axillary freckling Lisch nodules on iris Phaeochromocytoma Renal artery stenosis
What is Conn’s syndrome ?
Primary hyperaldosteronism causing hypertension, hypokalaemia and inhibition of renin secretion
Which test can be done to diagnose Conn’s syndrome ?
Serum aldosterone: renin levels
Conn’s: high Aldosterone:renin ratio
How can you test for Cushing’s ?
9am cortisol
12pm midnight cortisol (if low then very strong negative predictive value that it is not Cushing’s)
Low dose dexamethasone suppression test
0.5 mg dexamathasone every 6hrs for 48 hours ( if cortisol not suppressed then Cushing’s)
Which tests can help differentiate Cushing’s syndrome from Cushing’s disease?
High dose Dexamethasone suppression test- pituitary tumour secreting ACTH shows some suppression in cortisol. Adrenal ACTH tumours are not suppressed.
Inferior petrosal sinus sampling (IPSS)- sampling of the pituitary for an ACTH secreting tumour
85% cause of endogenous Cushing’s syndrome is Cushing’s disease
Why is IPSS preferred to High dose dexamethasone suppression test?
High dose dexamethasone test has a 20% false positive rate
List 3 features of MEN2b ?
Phaeochromocytoma
Medullary thyroid cancer
G.I tract mucocutaenous neuromas
Differential diagnosis of an adrenal mass
Phaeochromocytoma
Conns syndrome
Cushing’s syndrome
Treatment for a phaeo
Medical emergency
1- alpha blockade (phenoxybenzamine)
Leads to sudden BP drop so give fluids
2- beta blockade
To treat reflex tachycardia
Surgery
What is pseudo Cushing’s syndrome
Obesity can change your metabolism of cortisol and produce a picture that looks like Cushings
List the endogenous and exogenous causes of Cushing’s syndrome
Endogenous Pituitary dependent Cushing’s disease (85%) Adrenal adenoma (10%) Ectopic ACTH ( 5%)
Exogenous
Oral steroids
