Chemical Pathology 6 - Adrenal Flashcards
(35 cards)
Recall the 3 zones of the adrenal gland and what is produced in each one
Zone glomerulosa = aldosterone
Zona fasiculata = cortisol
Zona reticularis = androgens
What catecholamines are secreted by adrenals?
ADrenaline (peripheral - noradrenaline)
Causes of wasted adrenal glands
Addison’s
Long term steroids
Causes if hyperplastic adrenal glands
Cushing’s disease
ectopic ACTH
What is the blood supply to the adrenals like
Through IVC to adrenal vein
L → drains to L renal vein
R → drains to IVC
What is Schmidt’s syndrome?
Primary hypothyroisidm AND
- low t4, high TSH
Addisson’s disease (primary adrenal failure)
- hypoglycaemia (GC def), low sodium + high potassium (MC def)
AKA Polyglandular autoimmune syndrome type II
What are autoantibodies directed against in Schmidt’s syndrome?
Thyroid and adrenals
What else can give a similar picture to Schmidt’s syndrome?
TB
Causes of Addison’s
Autoimmune (UK most common)
TB (worldwide most common)
Metastasis
Haemorrhage (Waterhouse-Friedrichson Syndrome)
Iatrogenic
Features of Addison’s disease
What’s the test for Addisson’s, and how should it be performed?
SynACTHen test
Following adminstration of synthetic ACTH, check cortisol at 30 and 60 mins
What results would you expect from the short synACTHen test in Addison’s?
ACTH = >100ng/dL; Cortisol = <10nM (30mins); Cortisol = <10nM (60mins)
Not making any cortisol in response to ACTH challenge = failure
How would you manage Addison’s disease?
IV 0.9% saline (1L/hour)
IV hydrocortisone (sick day rules)
What is the expected electrolyte abnormality in untreated primary adrenal failure?
Hyponatraemia, hyperkalaemia
What are the 3 differentials to consider when a patient with severe hypertension also has an adrenal mass?
- Phaeochromocytoma (medullary tumour)
- Conn’s syndrome (aldosterone-secreting tumour - zona glomerulosa)
- Cushing’s (zona fasciculata tumour secreting cortisol)
What are some disorders associated with phaeochromocytomas?
MEN2 → parathyroid tumour, medullary thyroid cancer, phaeo
von Hippel Lindau syndrome → phaeo, renal cell carcinoma, renal cysts, haemangioblastoma
Neurofibromatosis type 1 → phaeo, peripheral/spinal neurofibromas, café au lait spots, etc.
How would you test for phaechromocytomas?
Urinary catecholamines - high
How should phaeochromocytoma be treated?
Medical emergency
- Immediate alpha blockade (phenoxybenzamine) → reflex tachycardia
- Add beta blockade (deals with reflex tachycardia)
- Surgery
What are the expected aldosterone and renin levels in untreated Conn’s syndrome?
High aldosterone, low renin
Primary hyperaldosteronism -> adrenals autonomously secrete aldosterone → HTN → supress renin production at JGA
What are the expected aldosterone and renin levels in untreated Cushing’s syndrome?
Both low
At high concentrations, cortisol activates MR – 11b-hydroxysteroid dehydrogenase usually degrades cortisol to stop this happening but at concentration, the enzyme is overwhelmed → HTN
What 3 tests can be used to screen for Cushing’s?
- 9am cortisol
- 12am salivary cortisol (low = normal)
- LDDST (at 11pm → 1mg dexamethasone and measure cortisol before 9am next day)
What would LDDST show in Cushing’s disease?
cortisol will not be suppressed
What is the diagnosis in a patient with symptoms of Cushing’s but a normal result in the low-dose dexamethosone suppression test?
Normal Suppression (i.e. pseudo-Cushing’s Syndrome in OBESITY)
What is the diagnosis in a patient with symptoms of Cushing’s but only a very slightly suppressed cortisol in the low-dose dexamethosone suppression test?
Cushing’s syndrome of indeterminate cause
