Lecture 2 – Adrenal Flashcards
What do the cortex and the medulla of the adrenal glands produce?
The cortex produces adrenaline and the medulla produces catecholamines.
What are the different layers of the adrenal medulla and what do they produce?
The zona glomerulosa produces mineralacorticoids such as aldosterone
The zona fasciculata produces glucocorticoids such as cortisol
The zona reticularis produces androgens such as DHEA
What is congenital adrenal hyperplasia and how does it occur?
It is a number of autosomal recessive conditions that result in problems with enzymes in the synthesis of steriods. Typically there is blockage of the cortisol pathway resulting in overproduction of DHEA. This can cause female babies to be born with virilised genitalia.
What deficieny most commonly causes CAH and how would this be tested diagnostically?
21-hydroxylase enzyme is most commonly deficient and this causes a lack of conversion to 17OHP. This means that 17OHP levels can be measured before and after ACTH is given to detect 17-hydroxylase deficiency.
Why does DHEA production increase when there is a deficiency in 21-hydroxylase?
As there are no mineralcorticoids or glucocorticoids being produced there is greatly reduced negative feedback to the pituitary. This means excessive ACTH is produced resulting in overproduction of androgens.
Why is CAH a medical emergency?
The child is not producing enough glucocorticoids so will go into adrenal crisis if not given cortisol.
What is the growth pattern of an undiagnosed child with CAH?
They will grow quickly however their growth plates will fuse early due to excessive androgens. This will result in short stature later in life.
What is an adrenal incidentaloma?
An adrenal mass that is dicovered icidentally when investigating other things.
What is adrenocortical carcinoma and how common is it?
It is a highly malignant tumour but is rare at only 2-11% of adrenal masses.
It is hard to differentiate between benign and malignant adrenal masses, why is this?
Imaging of the adrenals is difficult so hard to tell if they are benign.
Once an adrenal mass has been identified what can be looked at other than imaging?
Can look at hormone levels to see if the tumour is hypersecreting. All layers of the adrenals can hypersecrete with a tumour.
What three conditions must you exclude when looking at bloods for an adrenal mass?
Cushings
Phaeochromocytoma - adrenaline
Primary Hyperaldosteronism - renin levels high
What is phaeochromocytoma and what would you test to exclude this?
This is a hypersecretory tumour in the cortex of the adrenal gland. This could be excluded by looking at plasma metanephrines because these are the breakdown products of adrenaline so would be increased with phaeochromocytoma.
How would you exclude cushings when looking at an adrenal mass?
An overnight dexamethasone supression test would be used. This provides negative feedback to the pituitary which should decrease ACTH and cortisol if it is was not cushings. Also do 24 hr urinary free cortisol.
How would you exclude hyperaldosteronism with an adrenal mass?
measure renin and aldosterone levels, always test pairs of hormones (diagnostic pairs) e.g. ACTH and cortisol.
