Adrenal Structure & Function

Question 1

What hormone is secreted by the zona glomerulosa (ZG)?

Answer 1

Mineralocorticoids (e.g., aldosterone)

Question 2

What hormone is secreted by the zona fasciculata (ZF)?

Answer 2

Glucocorticoids (e.g., cortisol)

Question 3

What hormone is secreted by the zona reticularis (ZR)?

Answer 3

Androgens (e.g., DHEA, DHEAS, androstenedione)

Question 4

What is secreted by the adrenal medulla?

Answer 4

Catecholamines (80% adrenaline, 20% noradrenaline)

Question 5

What is the basic structure of all steroid hormones?

Answer 5

Cyclopentanoperhydrophenanthrene (3 cyclohexane + 1 cyclopentane ring)

Question 6

What controls glucocorticoid secretion?

Answer 6

The HPA axis and ACTH from the pituitary

Question 7

What controls aldosterone secretion?

Answer 7

Angiotensin II

Question 8

Which adrenal hormone is most abundant daily?

Answer 8

Adrenal androgens (>20 mg/day)

Question 9

What is the daily production of cortisol?

Answer 9

10 to 20 mg/day

Question 10

What is the daily production of aldosterone?

Answer 10

100 to 150 mcg/day

Question 11

How much more cortisol is in serum compared to aldosterone?

Answer 11

2000 times more

Question 12

Why doesn’t cortisol activate mineralocorticoid receptors?

Answer 12

It’s inactivated by 11β-HSD type 2

Question 13

When can cortisol exert mineralocorticoid effects?

Answer 13

At high concentrations

Question 14

What triggers catecholamine release from the adrenal medulla?

Answer 14

Exercise or imminent danger (fight-or-flight)

Question 15

What are effects of catecholamines?

Answer 15

Increased HR, vasoconstriction, bronchodilation, increased metabolism

Question 16

What is the half-life of catecholamines?

Answer 16

About 2 minutes

Question 17

What is the most common cause of primary adrenal insufficiency?

Answer 17

Autoimmune adrenalitis

Question 18

What skin feature is commonly seen in Addison’s disease?

Answer 18

Buccal and skin hyperpigmentation

Question 19

What electrolyte abnormalities are found in Addison’s?

Answer 19

Hyponatremia and hyperkalemia

Question 20

What is the definitive diagnostic test for adrenal insufficiency?

Answer 20

Short synacthen (ACTH stimulation) test

Question 21

What result confirms adrenal insufficiency on a 9 am cortisol test?

Answer 21

< 100 nmol/L

Question 22

What is a normal cortisol response 30 mins after Synacthen?

Answer 22

> 540 nmol/L

Question 23

What is the main hormonal deficiency in adrenal crisis?

Answer 23

Mineralocorticoid deficiency

Question 24

What is the predominant sign of adrenal crisis?

Answer 24

Hypotensive shock

Question 25

How is adrenal crisis treated initially?

Answer 25

IV fluids, dextrose, IV hydrocortisone, treat underlying cause

Question 26

What is the typical daily hydrocortisone dose?

Answer 26

10 mg morning, 5 mg lunch, 5 mg evening

Question 27

What mineralocorticoid is used in Addison’s?

Answer 27

Fludrocortisone 100 mcg daily

Question 28

What are the “sick day rules” for patients with adrenal insufficiency?

Answer 28

Never stop steroids, double dose during illness, use IM/IV if unable to take PO

Question 29

What is a common cause of secondary adrenal insufficiency?

Answer 29

Long-term exogenous steroid use

Question 30

What features differentiate it from primary insufficiency?

Answer 30

No hyperpigmentation, no hyperkalemia, hypoglycemia more common

Question 31

Commonest cause of Addison’s is TB – TRUE or FALSE?

Answer 31

FALSE (autoimmune is most common)

Question 32

Absence of adrenal antibodies excludes Addison’s – TRUE or FALSE?

Answer 32

FALSE

Question 33

Secondary adrenal insufficiency requires mineralocorticoid replacement – TRUE or FALSE?

Answer 33

FALSE

Question 34

ACTH is raised in Addison’s disease TRUE or FALSE?

Answer 34

TRUE

Question 35

What is the most common cause of Cushing’s syndrome?

Answer 35

Exogenous corticosteroid use

Question 36

What is Cushing’s disease?

Answer 36

ACTH-secreting pituitary adenoma causing hypercortisolism

Question 37

Name two ACTH-independent causes of Cushing’s.

Answer 37

Adrenal adenomas and carcinomas

Question 38

What are pseudo-Cushing’s states?

Answer 38

Alcoholism, depression, obesity, anorexia, bulimia

Question 39

What are three screening tests for Cushing’s?

Answer 39

24-hour urinary cortisol, 1 mg dexamethasone suppression test, late-night salivary cortisol

Question 40

What is the expected result in a normal dexamethasone suppression test?

Answer 40

9 am cortisol < 50 nmol/L

Question 41

What lab abnormalities are associated with Cushing’s?

Answer 41

Raised WBC, hyperglycemia, hypokalemic metabolic alkalosis