ChemPath: Adrenal Disease Flashcards
Patient tired and vomiting. TSH>50 and free T4 <5. What does this result suggest?
Primary hypothyroidism
What region of the adrenal gland makes cortisol?
zona fasciculata
What are the five layers of the adrenal gland?
- Capsule
- Glomerulosa
- Fasciculata
- Reticularis
- Medulla
What is Addison’s disease?
adrenal failure
What can cause adrenal glands to appear wasted?
Addison’s disease
Long-term steroid use
What can cause adrenal glands to become hyperplastic?
Cushing’s disease
Ectopic ACTH
By what factor is the output of cortisol from the adrenals greater than the output of aldosterone?
About 1000 (aldosterone is measured in picomoles, cortisol is measured in nanomoles)
How many arteries and veins do the adrenal glands have?
57 small arteries
1 vein
How is a blood sample to measure adrenal output taken?
A cannula is placed through the IVC into the adrenal vein
How is the venous drainage different for the left and right adrenal glands?
Left - drains into the left renal vein
Right - drains directly into the IVC
What is the term used to describe the co-existence of primary hypothyroidism and Addison’s disease?
Schmidt syndrome (though it is now called Polyglandular Autoimmune Syndrome Type 2)
Describe the short synacthen test.
- Measure cortisol and ACTH at the start of the test
- Administer 250µg synthetic ACTH by IM injection
- Check cortisol at 30 and 60 mins
- Healthy people should produce >550nM of cortisol within 30 mins
synACTHen results in patient with Addison’s
ACTH >100ng/dl
cortisol <10nM at both 30 and 60 min
What is a phaeochromocytoma?
adrenal medullary tumour secreting adrenaline
What is the differential diagnosis for hypertension with an adrenal mass?
- Phaeochromocytoma
- Conn’s syndrome
- Cushing’s syndrome
What is Conn’s syndrome?
Adrenal tumour secreting aldosterone
How can Conn’s syndrome be diagnosed?
High aldosterone: renin ratio as high blood pressure suppresses renin secretion
How can Conn’s syndrome be managed?
total adrenalectomy and spironolactone
What are the disastrous consequences of phaeochromocytoma?
- Severe hypertension
- Arrhythmia
- Death
Outline the treatment of phaeochromocytoma.
- Urgent alpha blockade (phenoxybenzamine or doxazocin or phentolamine)
- Some fluids may be given after the alpha-blocker to prevent reflex tachycardia
- A beta-blocker should be given after the alpha-blocker to prevent reflex tachycardia
- Patients should receive high-dose alpha and beta-blockade before surgery as the action of surgery can cause the release of catecholamines from the adrenals
Name three genetic syndromes associated with phaeochromocytomas.
- MEN2
- Von Hippel Lindau syndrome
- Neurofibromatosis type 1
Describe the levels of aldosterone and renin in Conn’s syndrome.
High aldosterone
Low renin
List some tests used in Cushing’s syndrome.
- 9am cortisol
- Midnight cortisol: take within 90 seconds
- Low-dose dexamethasone suppression test
- Inferior petrosal sinus sampling
Describe how low-dose dexamethasone suppression test is performed and results.
- The patient’s baseline ACTH and cortisol is measured at the start
- Then they are given 0.5mg dexamethasone every 6 hours for 48 hours
- This should suppress cortisol to <50nM
- If there is failure of suppression of cortisol, the patient should be sent for inferior petrosal sinus sampling
Low dose dexamethasone test comes back positive. What conclusion can you draw from this?
This person has Cushing’s syndrome of indeterminate cause.
What is inferior petrosal sinus sampling?
IPSS with CRH stimulation-→ cannula to pituitary glands into pituitary veins and ACTH levels measured- if very high= pituitary dependent
What proportion of endogenous Cushing’s syndrome is caused by Cushing’s disease?
85%
Exogenous causes of Cushing’s syndrome
Oral steroids
Herbal remedies containing steroids
What is pseudo-Cushing’s syndrome?
Obesity can change your metabolism of cortisol to produce a clinical syndrome that looks like Cushing’s syndrome
List three endogenous causes of Cushing’s syndrome.
85% Pituitary-dependent Cushing’s disease
10% Adrenal adenoma
5% Ectopic ACTH
What is this?
Adrenal Glands
