hypoadrenals Flashcards
steroid hormone synthesis- pathways, comparison and sex steroids
cholesterol forms 3 pathway- mineralocorticoid pathway, glucocorticoid pathway or sex steroids pathway all pathways are quite similar, but are tweaked by different HYDROGENASES testosterone converted into oestrogen using aromatase (although structures similar)
causes of adrenocortical failure
adrenal glands destroyed enyzmes in steroid synthesis pathway not working
causes of adrenal gland destruction
addisons disease due to TB (most common globally) autoimmune addisons (most common UK) congenital adrenal hyperplasia
features of addisons disease
due to aldosterone deficiency- postural hypotension due to cortisol deificiency- lethargic, weight loss with low appetite, hyperpigmentation and distributed in different places (eg scars), hirsutism may also have vitiligo (patches of skin have no pigmentation)
how adrenal gland looks with different causes of adrenal CORTICAL failure
if small and atrophied- due to autoimmune if large, due to TB, which fills gland with granulomas which are dysfunctional OR congenital hyperplasia, as high ACTH is driving growth
consequences of adrenocortical failure
low BP- main cause of death in addisons loss of salt in urine (hyponatraemic), thus hyeperkalaemia hypoglycaemia high ACTH- pigmentation
why pigmentation occurs in addisons
high ACTH, which is formed from POMC, which is broken into ACTH and MSH (and endorphins)
test for addisons and values of addisons
low Na/high K+ is suggestive of addisons measure 9am cortisol (should be high in normal patient) and ACTH (low in normal patient)- addisons patient will have around 100 ug cortisol to confirm, give 250ug synthetic ACTH using short synACTHen test, and measure cortisol response- addisons patient will be 150, we are typically above 600
congenital adrenal hyperplasia and hormones affected + effect of sex steroids DIAGRAM
most common cause 21-hydroxylase deficiency, which is either complete or partial- if complete, will survive for few weeks 1st arm- progesterone can’t be converted ino 11 deoxycorticosterone= no ALDOSTERONE 2nd arm- 17 OH progesterone can’t be converted into 11 deoxycortisol= no CORTISOL thus all precursors become sex steroids= EXCESS- females babies can have ambiguous genitalia
partial 21-hydroxylase deficiency- features
can survive as they make some cortisol/aldosterone often present later in life with hirsutism (changes in hair distribution and excess hair), virilisation in girls (male features- male pattern baldness, bigger clitoris, small breasts) and precocious puberty in body (too much adrenal testosterone)
11-hydroxylase deficiency- excess hormones and features
11 deoxycorticosterone can’t be converted into corticosterone, and deoxycortisol can’t form cortisol deoxycortisol doesn’t do anything, but deoxycorticosterone is like aldosterone- this becomes excess and causes hypertension and hypokalaemia thus cortisol/aldosterone deficient, but sex steroids and 11-deoxycortcicosterone in excess= virilisation as well
17 hydroxylase deficiency
11- deoxy and aldosterone in excess, and sex steroids/cortisol can’t form
