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Metabolism > Adrenal Cortex > Flashcards

Adrenal Cortex Flashcards

0
Q

What do the layers of the adrenal cortex secrete?

A

Zona glomerulosa: mineralocorticoids e.g. aldosterone

Zona fasciculata: glucocorticoids e.g. cortisol

Zona reticularis: androgens e.g. testosterone + glucocorticoids

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1
Q

What does the adrenal medulla secrete?

A

Noradrenaline & adrenaline (catecholamines)

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2
Q

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

A

Steroid hormones, therefore cholesterol is the precursor

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3
Q

What do glucocorticoids do?

A
  • stimulate gluconeogenesis & glycogenesis, protein catabolism, lipolysis at low levels but lipogenesis at higher levels
  • minor effect similar to mineralocorticoids
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4
Q

What do mineralocorticoids do?

A
  • Na+ retention

- K+ loss

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5
Q

What do androgens do?

A
  • testes formation
  • spermatogenesis
  • increase in muscle mass
  • decrease in fat deposition
  • estradiol production
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6
Q

What does a deficiency/excess in mineralocorticoids cause?

A

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

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

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7
Q

What does a deficiency/excess in androgens do?

A

Deficiency:

  • osteoporosis
  • erectile dysfunction
  • gynaecomastia

Excess:

  • clitoromegaly (females)
  • hypotension
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8
Q

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

A

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)
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9
Q

What are the biochemical features in Addison’s disease?

A

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

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10
Q

How can Addison’s disease be diagnosed?

A

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)

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11
Q

What is the mechanism of Addison’s disease?

A

Autoimmune destruction of adrenal cortex

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

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12
Q

What is the treatment for Addison’s disease?

A 
Glucocorticoid & mineralocorticoid replacement (using hydrocortisone & fludrocortisone) 
Monitor cortisol levels daily 
Restore to normal weight 
Supress plasma renin 
Restore serum electrolytes to normal
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13
Q

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

A

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)

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14
Q

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

A
  • 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)
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15
Q

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

A
  • pituitary tumour (benign adenoma)
  • adrenal tumour/hyperplasia
  • ectopic ACTH-secreting tumour
  • cortisol-secreting tumour
  • steroid treatment
16
Q

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

A
  • [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)

17
Q

What is the treatment for Cushing’s syndrome?

A

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)
18
Q

What is the difference between primary and secondary gland failure?

A

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

Metabolism (20 decks)

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