Mineralcorticoids

Question 1

mineralocorticoids are produced in which location?

Answer 1

Zona glomerulosa

Question 2

The final step of aldosterone synthesis is

Answer 2

The conversion of 18-OHcorticosterone via aldosterone synthase

Question 3

what are the main regulators of aldosterone synthesis ?

Answer 3

• large amounts of ACTH can increase secretion
• hyperkaleamia of 10%
• low plasma Na (10%)
• renin-ag system main regulator (via ag2)

Question 4

summarise the 2 types of MC receptors

Answer 4

• different affinities for aldosterone
• Low= GR
  [cortisol] > [aldosterone]
  High- MR
  aldosterone affinity = cortisol affinity
  but [cortisol] > [aldosterone]

Question 5

what are the symptoms of syndrome of apparent MC excess?

Answer 5

• severe hypertension
• hypokalaemia
• low renin
• low aldosterone /normal, not high as expected
• increased Na retention

Question 6

AME is caused by

Answer 6

• a mutation to the 11b-HSD2 enzyme
• usually converts cortisol- cortisone (inactive)
• enzyme high levels in kidney (tissue specific)
• the inactive form of cortisol allows for the binding of MC to MR
• cortisol prevents binding off MC
• cortisol activates MR
• can occur in cushings due to starvation of enzyme

Question 7

role of SD2

role of SD1

Answer 7

• allows MR to bind to aldosterone

- role in obesity related disorders

Question 8

mechanisms of action of aldosterone include

Answer 8

• action in DCT/ CD/ ileum, jejunum
• increased protein synthesis of Na/K ATPases , Na channels, K channels
• increased localization of channels into their membranes
• increased activity of NHE3 exchanger
• sweat glands/salivary

Question 9

peripheral effects include

Answer 9

• hydrogen ion loss
• metabolic alkalosis
• H20 reabsorption
• Na reabsorption
• regulation of BP
• increased circulating BV
• may lead to CHF

Question 10

hyperaldosteronism can be either

Answer 10

primary- autonomous production of aldosterone

-secondary- increased levels due to high renin levels

Question 11

conns syndrome (1 aldosteronism) is caused by

Answer 11

• hyperplasia of the adrenal cortex
• adrenal adenoma in zona G
• renin levels normal

Question 12

symptoms of conns syndrome include

Answer 12

• hypertension
• alkalosis
• hypoK
• muscle weakness
• cardiac arrhythmias

treatments

• spironolactone (MR antag)
• surgery

Question 13

secondary hyperaldosteronism is caused by

Answer 13

• renal artery stenosis
• diuretic therapy
• XS liquorice ingestion - 11BHSD inhibition
• renin levels are high

Question 14

Addisons disease (aldosterone deficiency) can lead to…

Answer 14

• Ion imbalance
  – Hyperkalaemia
• Hypotension