Adrenal disorders Flashcards
What is the effect of angiotensin II on the adrenals?
activation of the following enzymes:
Side Chain Cleavage 3 Hydroxysteroid dehydrogenase 21 hydroxylase 11 hydroxylase 18 hydroxylase
What does aldosterone do?
Controls blood pressure, sodium and lowers potassium
What does ACTH do?
Activation of the following enzymes
Side Chain Cleavage:
3 Hydroxysteroid dehydrogenase
21 hydroxylase
11 hydroxylase
17 hydroxylase
What is Addisons’ disease?
Primary adrenal failure
Autoimmune
destroys adrenal cortex
TB of adrenal gland is commonest cause * worldwide other than autoimmune in developed countries
Pituitary starts secreting lots of ACTH and hence MSH
Symptoms of Addisons’?
LOW SODIUM HIGH POTASSIUM LOW GLUCOCORTICOIDS
Increased pigmentation
Autoimmune vitilligo
No cortisol or aldosterone, so low blood pressure
Hypoglycaemia
Hyponatraemia
Those who have a high levels of ACTH pathologically become tanned because?
protein that is cleaved to form a number of smaller peptides, including ACTH, MSH and endorphins
What are the two causes of adrenocortical failure?
Adrenal glands destroyed
Enzymes in the steroid synthetic pathway not working
What is the congenital cause of adrenocortical failure?
Congenital adrenal hyperplasia
What are the consequences of adrenocortical failure?
- Fall in blood pressure
- Loss of salt in the urine
- Increased plasma potassium
- Fall in glucose due to glucocorticoid deficiency
- High ACTH resulting in increased pigmentation
- Eventual death due to severe hypotension
What are the tests done for Addison’s?
9am cortisol = low
ACTH = high
Short synACTHen test:
Give 250ug synacthen IM
–> Measure cortisol response
Why can we not give aldosterone to a px?
Half life of aldosterone is too short for safe once daily administration
Why can we give Fludrocortisone?
Fluorine does not exist in natural steroids, so is presence slows metabolism substantially. Binds to MR and Gr = its half life is 3.5 hours which is short but you take it 3 times a day
What is the issue with giving oral hydrocortisone?
has too short half life for daily administration, causes late peaks when can be harmful for the px
What is given instead of hydrocortisone for cortisol replacement?
prednisolone:
longer half life, more potent than cortisol, 2.3x binding affinity than cortisol
What dose of prednisolone is available?
1mg, 2.5mg, 5mg* bit much*
Not enteric coated which slows absorptions
( This would be equivalent dose of 15-25mg hydrocortisone daily )
