Endo 7 - Hypoadrenal Disorders Flashcards
Which enzyme converts cholesterol to pregnenalone?
CP450
Which set of enzymes are switched on by ACTH?
Sex steroid enzymes
Cortisol synthesis enzymes
The pituitary produces ACTH in response to?
Stress
State 3 causes of adrenocortical failure
- Tuberculosis Addisons - worldwide
- Autoimmune Addisons - UK
- Congenital Adrenal Hyperplasia
Name some of the features of Addisons
Hypotension Hyperkalaemia Loss of salt in urine Fall in blood glucose High ACTH Pigmentation Vitiligo Eventual death due to hypotension
Why do Addison’s patients get vitiligo?
Vitiligo is an autoimmune disease where the body produces antibodies against melanin
autoimmune disease go hand in hand
Why do Addison’s patient get pigmentation?
Lack of cortisol causes high ACTH
ACTH comes from POMC
POMC = ACTH + MSH
MSH is melanocyte stimulating hormone so causes pigmentation of skin
Why do Addison’s patients get hypotension?
Fall in aldosterone
Why is there excess loss of sodium in Addison’s patients?
fall in aldosterone = reduced reabsorption of sodium
State some tests for Addisons
- 9am cortisol level - would be high in a normal person
- measure ACTH - this would be high in Addisons
- synACTHen - functioning adrenals - produce cortisol
Addison’s patient will not be able to produce cortisol
could also measure glucose, sodum, potassium
What is the most common cause of congenital adrenal hyperplasia?
21-b-hydroxylase
What are the two degrees of CAH that you can have?
partial or complete
Why are foetus’ in utero fine?
They have maternal cortisol and aldosterone so don’t need to produce any of their own
Which hormones are absent in 21-hydroxylase deficiency>?
cortisol and aldosterone
What effect does 21-hydroxylase deficiency have on sex steroids?
Precursors are funnelled towards the sex steroid synthesis pathway so you get an increase in adrenal sex steroids
What will happen to a baby born with complete 21 hydroxylase deficiency?
Salt losing crisis straight away as they have no aldosterone
What are the two main features of complete 21 hydroxylase deficiency?
Hypotension
Virilisation - female babies born with ambiguous genitalia
Describe the presentation of partial 21 hydroxylase deficiency?
may present much later on
may present with effects of excess adrenal androgens
Name 2 other types of congenital adrenal hyperplasia?
- 11 beta hydroxylase deficiency
- 17 beta hydroxylase deficiency
What is the precursor that builds up in 11 hydroxylase deficiency CAH?
build up of 11 deoxycorticosterone
What is 11 deoxycorticosterone?
aldosterone receptor agonist
What will a patient with 11 beta hydroxylase deficiency present with?
- will NOT have salt losing crisis as have an aldosterone receptor agonist
- will present with having too much aldosterone
- e.g. hypertensive and hypokalaemic
- virilised, hypertension,
Describe and explain the presentation of 17 beta hydroxylase deficiency?
- high levels of aldosterone
- so hypertensive and hypokalaemic
- present with absent puberty as missing sex steroids and cortisol
- a lot of infections as need cortisol to deal with infection
