Cushings

Question 1

What is Cushing’s syndrome?

Answer 1

Prolonged levels of glucocorticoids (cortisol)

Question 2

What are the 2 groups of corticosteroid hormones? Give an example of each

Answer 2

• Glucocorticoids (e.g., cortisol)
• Mineralocorticoids (e.g., aldosterone)

Question 3

Where specifically is cortisol produced?

Answer 3

Zona fasciculata

Question 4

Where are mineralocorticoids produced?

Answer 4

Zona glomerulosa

Question 5

What is produced from the Zona glomerulosa?

Answer 5

Mineralocorticoids such as aldosterone

Question 6

What is produced from the Zona fasciculata?

Answer 6

Corticosteroids e.g. cortisol
And a small amount of androgens

Question 7

What is produced from the zona reticularis?

Answer 7

produces and secretes androgens such as dehydroepiandrosterone (DHES). It also secretes a small amount of corticosteroids.

Question 8

What is released from the medulla? What is the name of the cells they are released from?

Answer 8

Catecholamines e.g. adrenaline
Chromaffin cells

Question 9

What are some symptoms of Cushing’s? (8)

Answer 9

o Weakness
o Facial fullness
o Weight gain
o Low mood
o Decreased libido
o polydipsia
o polyuria
o Increased frequency of infection

Question 10

Which sign of Cushing’s is specific to Cushing’s disease?

Answer 10

o Hyperpigmentation of the skin in patients with Cushing’s disease (due to high ACTH levels)

Question 11

What are some signs of Cushing’s? (12)

Answer 11

o Round face (known as a “moon face”)
o Central (truncal) obesity
o Abdominal striae (stretch marks)
o Enlarged fat pad on the upper back - dorsal fat pad
o Proximal limb muscle wasting (with difficulty standing from a sitting position without using their arms) - proximal myopathy
o Male pattern facial hair in women (hirsutism)
o Easy bruising and poor skin healing
o Hyperpigmentation of the skin in patients with Cushing’s disease (due to high ACTH levels)
○ ACTH is stimulating melanocytes to produce melanin
○ This is absent if the cause is an adrenal adenoma or exogenous steroids
o Hypertension
o Signs of tumour in Cushing’s disease e.g. headaches, visual field defects
o Acne

Question 12

What type of ABG is seen in Cushing’s?

Answer 12

Hypokalaemic metabolic alkalosis

Question 13

What are some complications of Cushing’s? (5)

Answer 13

• hypertension
• diabetes
• obesity
• Metabolic syndrome
• Osteoporosis

Question 14

What is Nelson’s syndrome?

Answer 14

• Nelson’s syndrome = development of an ACTH-producing pituitary tumour after the surgical removal of both adrenal glands due to a lack of cortisol and negative feedback. It causes skin pigmentation (high ACTH), bitemporal hemianopia and a lack of other pituitary hormones.

Question 15

Which drugs can be used to treat Cushing’s before surgery? (3)

Answer 15

Metyrapone, ketoconazole + mitotane

Question 16

What are the causes of Cushing’s? (4)

Answer 16

o C – Cushing’s disease (a pituitary adenoma releasing excessive ACTH)
o A – Adrenal adenoma (an adrenal tumour secreting excess cortisol)
o P – Paraneoplastic syndrome – ACTH is released from a tumour somewhere other than the pituitary gland (ectopic ACTH) stimulating excessive cortisol release from the adrenal gland e.g. small cell lung cancer
o E – Exogenous steroids (patients taking long-term corticosteroids)

Question 17

What is the cause of Cushing’s disease?

Answer 17

Pituitary adenoma secreting acth

Question 18

What is the main investigation in Cushing’s?

Answer 18

Dexamethasone suppression tests

Question 19

What is the bodies normal response in the dexamethasone suppression test?

Answer 19

Suppressed cortisol due to negative feedback

Question 20

What is seen in Cushing’s in a low dose overnight test?

Answer 20

Failure to suppress morning cortisol

Question 21

What is seen in Cushing’s in a low dose 48 hour test?

Answer 21

Failure of cortisol suppression on day 3

Question 22

Which cause of Cushing’s has suppression of cortisol in a high dose 48hr test?

Answer 22

Pituitary adenoma

Question 23

Which 2 causes of Cushing’s have high acth?

Answer 23

Pituitary adenoma
Ectopic acth e.g. small cell lung cancer

Question 24

In which cause of Cushing’s is acth low? (2)

Answer 24

• ACTH is suppressed due to negative feedback on the pituitary when excess cortisol comes from an adrenal tumour (or endogenous steroids)

Question 25

What level of 24hour urinary free cortisol is suggestive of Cushing’s?

Answer 25

3 x upper limit of normal

Question 26

What is the normal variation of cortisol release?

Answer 26

Diurnal
Decreases in evening compared to morning

Question 27

What happens to the late night salivary cortisol measurement in Cushing’s?

Answer 27

Cortisol is not suppressed in evenings