Steroids

Question 1

Describe the structure of a steroid?

Answer 1

4 ring structure. with three six carbon rings and one five carbon ring

Question 2

anatomy of adrenal gland?

Answer 2

Adrenal glands weigh 4-5g
Two zones: adrenal cortex represents 90% of the gland and surrounds the medulla
Arterial blood supply comes from the renal arteries, aorta and inferior phrenic artery
Drains via a central vein into the inferior vena cava on the right and into the left renal vein on the left

Question 3

the rate limiting step is regulated by?

Answer 3

ACTH

Question 4

biosyntheiss of steroids?

Answer 4

Question 5

Eamples of sex steroids?

Answer 5

DHEA and androstenedione are the major examples. Converted in the periphery into oestrogens or androgens (testosterone).

Question 6

ACTH physiology reg?

Answer 6

Question 7

what stimulate ACTH release?

Answer 7

loss of fluid electrolytes (Na)

Question 8

primary addisons?

Answer 8

destruction of the adrenal cortex

Question 9

econdary addisons?

Answer 9

disorderes pituitary and jhypothalamic function. Suppression of hypothalamic/pituitary ACTH release by exogenous steroids

Question 10

Features of addisons?

Answer 10

Chronic
Anorexia (loss of appetite) and weight loss (>90%)
Tiredness
Weakness
Pigmentation (generalised, buccal, palmar creases, pressure areas)
Dizziness
Nausea, diarrhoea, abdominal pain
Reduced pubic/axillary hair, reuced libido in women

Associated conditions (autoimmune disease in most people)
 Vitiligo
 Other autoimmune diseases e.g. type 1 diabetes, primary hypothyroidism

Question 11

new causes of addisons?

Answer 11

Question 12

how to diagnose addisons

Answer 12

low morning cortisol and high ACTH

failure for cortisol to rise with synacthen (synthetic ACTH)

positive adrenal (21-hydroxylase) ntibodies if autotimme

Question 13

how much synacthen to give?

Answer 13

250micrograms IV or IM

measure serum cortisol 30 mins after

Question 14

treatmenr of addisons?

Answer 14

Hydrocortisone (to replace cortisol)
Fludrocortisone (to replace aldosterone)
Occasionally DHEA (to replace DHEA/sex steroids, esp in women with low libido etc)
Consider screening for other autoimmune conditions e.g. primary hypothyroidism
Education!
‘Adrenal crisis’ occurs if patients do not increase their steroid doses appropriately or if they miss them
Crisis can be life-threatening

Question 15

main causes of cyshings?

Answer 15

ACTH-dependent
Pituitary adenoma (Cushing’s disease) 60-70%
Ectopic ACTH 10%
ACTH-independent
Adrenal adenoma 10%
Adrenal carcinoma 8%

Question 16

signs of cushings?

Answer 16