Adrenal disorders - Addison's Flashcards
What is a steroid made from?
Cholesterol
Where in the adrenal gland is cortisol made?
Zona fasciculata
What is the effect of angiotensin II on adrenal glands?
Activates pathway from cholesterol to aldosterone + cortisol, by activating side-chain cleavage enzymes (hydroxylase enzymes)
What are the three actions of aldosterone?
Control blood pressure, sodium levels and lowers potassium concentration
What is the effect of ACTH on adrenal glands?
Activates pathway from cholesterol to aldosterone + cortisol, by activating side-chain cleavage enzymes (hydroxylase enzymes). Binds to zona fasciculata
What is the difference between angiotensin II and ACTH’s effect on adrenal glands?
Angiotensin II activates 18-hydroxylase, ACTH activates 17-hydroxylase
What are the key hydroxylases in the steroid synthesis pathway?
17 -> 21 -> 11 (cortisol)
21 -> 11 -> 18 (aldosterone)
From progesterone
What are the two acquired ways primary adrenal failure occurs?
Autoimmune Destruction, Tuberculosis
What is Addison’s disease?
When your adrenal gland does not produce enough steroid hormones aka primary adrenal failure
causes xs ACTH from pituitary due to negative feedback
What are the three signs of Addison’s disease?
Increased pigmentation, autoimmune vitiligo (white patches), low blood pressure
Why do Addison’s patients have a good tan?
Pro-opio-melanocortin (POMC) is released as a precursor to ACTH. Splits into ACTH and MSH (causes pigmentation)
Where do congenital cause of adrenocortical failure affect?
Hydroxylase enzymes not working in steroid synthesis pathway
Causes of adrenocortical failure
- TB addison’s (most common)
- Autoimmune addison’s (UK common)
- Congenital adrenal hyperplasia
What is the structural change adrenal glands go under in congenital adrenocortical failure and why?
Adrenal hyperplasia - adrenal glands don’t make enough cortisol, pituitary makes more ACTH to increase adrenal gland performance
What are the 6 presentations of adrenocortical failure?
Fatigue, breathlessness, vomiting, weight loss, postural hypotension, tanned
What are the 6 physiological consequences of adrenocortical failure?
Low blood pressure, low sodium (most important), high potassium, low glucose, high ACTH, loss of salt in urine
What is the eventual cause of death in untreated adrenocortical failure?
Severe hypotension
What is made in the adrenal cortex
Corticosteroids
3 types of corticosteroids
Mineralocorticoids, aldosterone
Glucocorticoids, cortisol
sex steroids, androgens and oestrogens
What are the three tests for Addison’s disease?
9am cortisol - low,
ACTH - high,
short synACTHen test (ACTH) - cortisol will go up if normal
- no response with addison’s
Why would you not give aldosterone injections?
Half-life of aldosterone is too short (would require lots of injections all day)
Treatment of primary adrenocortical failure
Replacement of cortisol and aldosterone
Hydrocortisone, prednisolone, fludrocortisone
What is used instead of aldosterone injections
Fludrocortisone
longer acting than aldosterone, agonist for mineralocorticoid receptor
What is the problem with hydrocortisone?
Oral hydrocortisone - short half life, so would need to give thrice daily
