adrenal disorders 1

Question 1

What does the adrenal cortex make?

Answer 1

corticosteroids. Mineralocorticoids - aldosterone. Glucocorticoids - cortisol. Sex steroids - androgens - oestrogens

Question 2

What is the precursor of all steroids?

Answer 2

cholesterol

Question 3

What does angiotensin II activate in the adrenals - what is the purpose and what enzymes are activated?

Answer 3

Angiotensin II switches on the enzymes that make aldosterone. These enzymes are side chain cleavage, 3-hydroxysteroid dehydrogenase, 21-hydroxylase, 11-hydroxylase, 18-hydroxylase

Question 4

What is the role of aldosterone?

Answer 4

To increase sodium reabsorption to increase blood pressure/volume, excrete potassium & protons

Question 5

What effects does ACTH have on the adrenals? What enzymes are activated?

Answer 5

ACTH switches on the enzymes to make cortisol in the adrenal cortex. The enzymes are side chain cleavage, 3-hydroxysteroid dehydrogenase, 17-hydroxylase, 21-hydroxylase, 11-hydroxylase

Question 6

What rhythm does cortisol have? When should they test for adrenal failure?

Answer 6

Diurnal rhythm. Should test for adrenal failure in the morning when it will normally be high. If low, problematic.

Question 7

What is addisons disease?

Answer 7

Adrenocortical failure - low aldosterone & cortisol

Question 8

What are 3 causes of adrenocortical failure and how common are they in UK/worldwide?

Answer 8

Autoimmune Addison’s disease (most common in UK), tuberculous addisons disease (most common worldwide), congenital adrenal hyperplasia

Question 9

What is the characteristic of adrenal failure - what hormones are low and which are high?

Answer 9

Aldosterone and cortisol are low, ACTH is high, MSH high

Question 10

What are the effects of low cortisol/aldosterone on the body - symptoms?

Answer 10

Hypoglycaemia, hypotension, increased potassium, fatigue, weakness, weight loss, vitiligo on skin, increased pigmentation

Question 11

Why does addisons cause a tan? What molecules are involved?

Answer 11

Pre-opio melanocortin (POMC) is a precursor peptide that forms ACTH and MSH (melanocyte stimulating hormone) when cleaved - MSH creates a tan

Question 12

What are the consequences of adrenocortical failure?

Answer 12

Hypotension, collapse, hypoglycaemia, weakness.

Question 13

What are the features of an addisonian crisis?

Answer 13

Fever, syncope, convulsions, hyponatraemia

Question 14

What is the test for addisons?

Answer 14

9am cortisol low, ACTH high. Short synACTHen test - 250 ug synACTHen IM given, if adrenals can produce cortisol they will rise more than 600. in addisons only rises by a bit.

Question 15

What is the treatment of adrenal failure?

Answer 15

For aldosterone, give fludrocortisone (50-100mcg daily) - has longer half life than aldosterone. For cortisol either give prednisolone 3mg once daily or hydrocortisone 3x a day with highest dose in the morning (10,5,2.5)

Question 16

What are the side effects of high doses of steroids? Why not give very low dose instead?

Answer 16

high doses immunosupression

low doses crisis

Question 17

What is congenital adrenal hyperplasia and what is the commonest cause?

Answer 17

The commonest cause is 21-hydroxylase deficiency.

Question 18

How does complete 21-hydroxylase deficiency present?

Answer 18

Cortisol and aldosterone completely absent. Presents in newborn. Survival less than 24 hours. Sex steroids (androgens) in excess - neonates present with addisonian crisis and girls may have ambiguous genitalia (virulisation)

Question 19

How does partial 21-hydroxylase deficiency present?

Answer 19

Deficiency of cortisol and aldosteone, sex steroids in excess. Can survive. Problems include hirsutism, virilisation in girls, and preocious puberty in boys. Both born with big adrenal glands

Question 20

What is the treatment for 21-hydroxylase deficiency?

Answer 20

Prednisolone once daily considered better than hydrocortisone 3x daily

Question 21

What happens in 11 hydroxylase deficiency?What is in excess and what does this cause?

Answer 21

Aldosteorne and cortisol deficient. Excess 11-deoxycorticosterone & sex steroids. 11-deoxycorticosterone acts as aldosterone so we get those effects in excess –> hypertension, hypernatreamia, low K, hirsutism, virulisation, hypoglycaemia

Question 22

What happens in 17-hydroxylase deficiency?

Answer 22

Deficient cortisol + sex steroids, excess aldosterone. Hypertension, hypoglycaemia, low K, sex steroid deficiency.

Question 23

What is the mechanism of aldosterone

Answer 23

Aldosterone stimulates sodium reabsorption in DCT and collecting duct in kidneys by increasing sodium - potassium ATPase transporter so that sodium reabsorbed and potassium & protons excreted. Increase sodium reabsorption so increase water reabsorption and thus blood volume and pressure.

Question 24

How is aldosterone regulated?

Answer 24

Renin secreted by juxtaglomerular cells in response to low blood pressure. Renin converts angiotensin I to II. Angiotensin II switches on the enzymes in the adrenal cortex to make aldosterone.