Adrenal II Flashcards
effects of catecholamines on alpha receptors
vasoconstriction, pupil dilation, intestinal relaxation, sphincter contraction, pilomotor contraction, bladder sphincter contraction
effects of catecholamines on beta receptors
vasodilation, cardioacceleration, cardiac inotropy, uterine relaxation, bronchodilation, glycogenolysis, lipolysis, bladder relaxation
symptoms of adrenal insufficiency
weakness and fatigue, loss of appetite, GI symptoms (nausea, vomiting, abdominal pain, diarrhea).
minor symptoms include salt craving, postural dizziness, muscle and joint pain
signs of adrenal insufficiency; mechanisms of these signs
weight loss, incr. skin pigment (incr- melanocyte stimulating hormone and ACTH share a precursor molecule, POMC. in primary insufficiency, there is high ACTH and therefore high MSH), low BP, vitiligo (related to autoimmune hypothyroidism- both of these are usually autoimmune problems).
Lab findings in adrenal insufficiency and reasons for them
low Na, high K, low blood sugar (in kids more than adults)
sodium: aldo causes sodium retention. without it, you have sodium and water wasting. ADH will go up to prevent hypovolemia, which further dilutes sodium
K: no aldo, so less K secretion in distal nephron
sugar: if it happens, it is due to a loss of cortsol effects on hepatic glucose storage and output
Dx of adrenal insufficency
low cortisol is the hall mark
low cortisol is normal at some times during the day
early morning cortisol < 5 mgm/dl suggests adrenal insufficiency; >15 makes it unlikely
testing response to synthetic ACTH is the benchmark for diagnosis- if there isn’t a rise after a dose of ACTH, you can infer an adrenal defect
normal response is to 250 mcg rise
causes of primary adrenal insufficiency
- inherited disorders of adrenal steroidogenesis:: 21 hydroxylase deficiency is the most common and causes congenital adrenal hyperplasia
other reasons possible but I’m not going to memorize them - autoimmunity
- adrenoleukodystrophy
- congenital adrenal hypoplasia
- acquired disorders: adrenal hemorrhage, infectious adrenalitis (TB or fungi, AIDS)
What happens in CYP21 hydroxylase deficiency: pathophysiology
cause of congenital adrenal hyperplasia
no ability to make aldo or cortisol
adrenals only make sex hormones
high levels of 170hydroxyprogesterone because there is backup of 21 hydroxylase substrates
adrenal hyperplasia because the brain knows it needs more cortisol and there are very high levels of ACTH
CYP21 hydroxylase deficiency: signs and symptoms
babies have cortisol deficiency and salt wasting. they become very very dangerously hypotensive within a few days-wks after birth
girls have ambiguous genitalia in severe forms
others may have virulization, precocious puberty. may be so mild that it presents similar to PCOS
males can get adrenal rests on the testes (tumors)
Tx of 21 hydroxylase deficiency
prevents adrenal crisis
lowers androgens in women
prevents adrenal rests on testes
What is another cause of congenital adrenal hyperplasia (not 21-hydroxylase deficiency)
3 beta HSD deficiency.
looks just like 21 hydroxylase deficiency but DHEA is INCREDIBLY high (even higher than in 21 hydroxylase deficiency, since there isn’t any androstenedione) and the 17-OH progesterone is low
autoimmunity and primary adrenal insufficiency
look for antibodies against cyp 21
think about auto immune polyglandular syndrome
How does adrenoleukodystrophy result in primary adrenal insufficiency?
adrenoleukodystrophy is a defect in fatty acid oxidation that causes an accumulation of very long chain fatty acids in the blood
can disrupt adrenal function
Causes of adrenal hemorrhage
anticoagulation, antiphospholipid antibody syndrome, sepsis,
treatment of adrenal insufficiency
acutely, replace intravascular volume and replace glucocorticoids at higher stress levels
chronically, replace glucocorticoids at physiologic levels, replace mineralocorticoids as needed, and adjust glucocorticoid levels up when stress occurs. encourage use of a medical alert bracelet
