Adrenal Cortex

Question 0

What do the layers of the adrenal cortex secrete?

Answer 0

Zona glomerulosa: mineralocorticoids e.g. aldosterone

Zona fasciculata: glucocorticoids e.g. cortisol

Zona reticularis: androgens e.g. testosterone + glucocorticoids

Question 1

What does the adrenal medulla secrete?

Answer 1

Noradrenaline & adrenaline (catecholamines)

Question 2

What types of hormones does the adrenal gland secrete? What is the precursor?

Answer 2

Steroid hormones, therefore cholesterol is the precursor

Question 3

What do glucocorticoids do?

Answer 3

• stimulate gluconeogenesis & glycogenesis, protein catabolism, lipolysis at low levels but lipogenesis at higher levels
• minor effect similar to mineralocorticoids

Question 4

What do mineralocorticoids do?

Answer 4

• Na+ retention

- K+ loss

Question 5

What do androgens do?

Answer 5

• testes formation
• spermatogenesis
• increase in muscle mass
• decrease in fat deposition
• estradiol production

Question 6

What does a deficiency/excess in mineralocorticoids cause?

Answer 6

Deficiency: decrease in Na+, increase in K+ —> dehydration due to osmotic diuresis

Excess: increase in Na+, decrease in K+ —> hypertension (high [salt] circulating)

Question 7

What does a deficiency/excess in androgens do?

Answer 7

Deficiency:

• osteoporosis
• erectile dysfunction
• gynaecomastia

Excess:

• clitoromegaly (females)
• hypotension

Question 8

What does a deficiency in cortisol cause? What are the signs and symptoms?

Answer 8

Addison’s disease

Non-specific S&S:

• weight loss
• weakness
• fever
• depression
• impotence
• amenorrhoea
• low libido
• abdominal pain
• myalgia
• nausea

Specific S&S:

• hyperpigmentation (ACTH build up - minor effect similar to alpha-MSH, stimulates melanin production)
• postural hypotension (BP drops when standing up)

Question 9

What are the biochemical features in Addison’s disease?

Answer 9

Natraemia (low Na+)
Hyperkalaemia (high K+)
High urea
Hypoglycaemia

Question 10

How can Addison’s disease be diagnosed?

Answer 10

Test [cortisol] (morning)
Syacthen test (synthetic ACTH —> won’t stimulate production)
[ACTH]blood (high)
[renin]plasma (low - mineralocorticoids cause an increase in renin)
adrenal antibodies (presence of)

Question 11

What is the mechanism of Addison’s disease?

Answer 11

Autoimmune destruction of adrenal cortex

(or: TB, surgical removal of adrenal cortex, haemorrhage/infarction/infiltration of adrenal cortex, or adrenal leucodystrophy)

Question 12

What is the treatment for Addison’s disease?

Answer 12

Glucocorticoid & mineralocorticoid replacement (using hydrocortisone & fludrocortisone) 
Monitor cortisol levels daily 
Restore to normal weight 
Supress plasma renin 
Restore serum electrolytes to normal

Question 13

What is an Addisonian crisis? What is the emergency treatment? How can it be distinguished from a diabetic coma?

Answer 13

Deficiency of corticoids leading to osmotic diuresis —> low circulating volume —> low perfusion to brain —> DEATH

Hydrocortisone + fludrocortisone, replace fluids, dextrose (for hypoglycaemia)

Hypotension (diabetic coma = hypertension)

Question 14

What are the general signs and symptoms of Cushing’s syndrome?

Answer 14

• central adiposity
• weight gain
• depression
• insomnia
• low libido
• thin skin (easily bruised)
• hair growth
• acne
• muscle weakness & wasting (thin arms and legs)
• impaired glucose tolerance
• plethoric (flushed) moon face
• buffalo hump (dorsal fat pad)
• purple striae (stretch marks)

Question 15

What are some of the causes of Cushing’s syndrome?

Answer 15

• pituitary tumour (benign adenoma)
• adrenal tumour/hyperplasia
• ectopic ACTH-secreting tumour
• cortisol-secreting tumour
• steroid treatment

Question 16

How can the cause of Cushing’s syndrome be diagnosed?

Answer 16

• [CRH] (high in pituitary tumour)
• [ACTH]plasma (high in pituitary/ectopic tumour)
• 24hr urinary excretion of cortisol (high in adrenal/ectopic tumour)
• dexamethasone suppression test

(low dose: no response to suppression of ACTH confirms Cushing’s syndrome; high dose: response = pituitary tumours = Cushing’s disease, no response = ectopic/adrenal tumour)

Question 17

What is the treatment for Cushing’s syndrome?

Answer 17

Trans-sphenoidal surgery to remove pituitary tumours

Pituitary irradiation (pituitary tumours)

Bilateral adrenalectomy (adrenal tumours)
(note: can cause Nelson's syndrome = uncontrolled pituitary growth and hyperpitutarism)

Question 18

What is the difference between primary and secondary gland failure?

Answer 18

Primary gland failure:
Failure of end organ gland -> reduced end hormone -> increased pituitary hormone (overcompensation)

e.g. primary hypothyroidism

Secondary gland failure:
Failure of pituitary gland -> reduced end hormone -> reduced pituitary hormone

e.g. secondary hypothyroidism