Adrenal Disorders (Hypo) Flashcards
What does the adrenal cortex make?
Corticosteroids
What is the definition of a steroid?
Comes from choelstrol
Where in the adrenal gland are corticosteroids made?
Adrenal cortex
What corticosteroids are made in the adrenal cortex?
- Mineralocorticoids (Aldosterone)
- Glucocorticoids (Cortisol)
- Sex steroids (Androgens, oestrogens)
What adrenal enzymes does angiotensin II activate?
- Side Chain Cleavage
- 3 Hydroxysteroid dehydrogenase
- 21 hydroxylase
- 11 hydroxylase
- 18 hydroxylase
What is aldosterone’s action?
Controls blood pressure, sodium and lowers potassium
What adrenal enzymes does ACTH active?
- Side Chain Cleavage
- 3 Hydroxysteroid dehydrogenase
- 21 hydroxylase
- 11 hydroxylase
- 17 hydroxylase
What enzyme has diurnal rhythm?
Cortisol
What is primary adrenal failure called?
Addison’s disease
What is Addison’s disease caused by in the UK?
Autoimmune disease where the immune system decides to destroy the adrenal cortex
What is commonest cause of Addison’s disease worldwide?
Tuberculosis
What does the pituitary secrete in Addison’s disease?
ACTH and hence MSH
Why does an Addison’s patient have low blood pressure?
No cortisol or aldosterone
What skin condition may coexist with Addison’s disease?
Autoimmune vitiligo
Why does an Addison’s patient have increased pitgmentation?
POMC is a large precursor protein that is cleaved to form a number of smaller peptides, including ACTH, MSH and endorphins
What are the pathophysiological causes of adrenocortical failure?
- Adrenal glands destroyed (2)
- Enzymes in the steroid synthetic
pathway not working (1)
What are the causes of adrenocortical failure?
1. Tuberculous Addison’s disease (commonest worldwide) 2. Autoimmune Addison’s disease (commonest in UK) 3. 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 is POMC?
Pro-opio melanocortin
Where is POMC synthesized?
Pituitary
What is POMC broken down into?
ACTH MSH Endorphins Enkephalins Other peptides
What tests do you preform once there is clinical suspicion for Addision’s?
- 9am cortisol = low
- ACTH = high
- Short synACTHen test
- Give 250 ug synacthen IM
- Measure cortisol response
How does an Addison’s patient respond to synACTH?
Cortisol at 9am = 100 (270-900)
Administer injection IM of synacthen
Cortisol at 9.30 = 150 (>600)nM
What is the treatment of adrenal failure?
- Prednisolone 3mg daily
or
Hydrocortisone three times daily (10 + 5 + 2.5) - Fludrocortisone 50 to 100 mcg daily
What is congenital adrenal hyperplasia most commonly caused by?
21-hydroxylase deficiency
Which hormones will be totally absent in complete 21-hydrosylase deficiency?
Aldosterone and cortisol
How long can you survive in complete 21-hydrosylase deficiency?
Less than 24hrs
Which hormones will be in excess in complete 21-hydrosylase deficiency?
Sex steroids and testosterone
What is the presentation of complete 21-hydrosylase deficiency?
As a neonate with a salt losing Addisonian crisis
Why is the foetus not affected by complete 21-hydrosylase deficiency in utero?
Foetus gets steroids across placenta
How may infant girls be affected by complete 21-hydrosylase deficiency?
Might have ambiguous genitalia (virilised by adrenal testo)
Which hormones are deficient in partial 21-hydrosylase deficiency?
Cortisol and aldosterone
Which hormones will be in excess in partial 21-hydrosylase deficiency?
Sex steroids and testosterone
At what age will they present?
Any age, as they survive
What is the main problem in later life in partial 21-hydroxylase deficiency for girls?
Hirsutism and virilisation
What is the main problem in later life in partial 21-hydroxylase deficiency for boys?
Precocious puberty
What is the main problem in later life in partial 21-hydroxylase deficiency due to?
Adrenal testosterone
