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Year Two - Endocrine System > Cushing's Syndrome > Flashcards

Cushing's Syndrome Flashcards

1
Q

What is Cushing’s syndrome?

A

It is defined as a condition in which there is prolonged elevation of endogenous or exogenous glucocorticoids – such as cortisol

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2
Q

What are the three classifications of Cushing’s syndrome?

A

Exogenous Cushing’s Syndrome

Endogenous Cushing’s Syndrome

Pseudo-Cushing’s

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3
Q

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

A

Exogenous Cushing’s Syndrome

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4
Q

What is exogneous Cushing’s syndrome?

A

It is caused by prolonged administration of glucocorticoids – such as prednisolone, hydrocortisone, etc

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5
Q

What are the two subclassifications of endogenous Cushing’s syndrome?

A

ACTH Dependent Cushing’s Syndrome

ACTH Independent Cushing’s Syndrome

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6
Q

What is ACTH dependent Cushing’s syndrome?

A

It is defined as elevated glucocorticoid levels related to excess ACTH production from the anterior pituitary gland

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7
Q

What are the two causes of ACTH dependent Cushing’s syndrome?

A

Cushing’s Disease

Paraneoplastic Syndrome

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8
Q

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

A

Cushing’s Disease

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9
Q

What is Cushing’s disease?

A

It is defined as a pituitary tumour, which secretes increased ACTH levels, resulting in adrenal hyperplasia, and therefore increased cortisol levels

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10
Q

What is paraneoplastic syndrome?

A

It refers to the production of increased ACTH related to ectopic secretion from tumours

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11
Q

What tumour is most commoly associated with Cushing’s syndrome?

A

Small cell lung cancer

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12
Q

What is ACTH independent Cushing’s syndrome?

A

It is defined as elevated glucocorticoid levels related to direct excess glucocorticoid secretion from the adrenal glands

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13
Q

What are the four causes of ACTH independent Cushing’s syndrome?

A

Adrenal Adenoma

Adrenal Carcinoma

Micronodular Adrenal Dysplasia

McCune Albright Syndrome

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14
Q

What is pseudo-Cushing’s?

A

It is defined as a group of conditions which mimics Cushing’s syndrome; however, is secondary to other factors

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15
Q

What are the two causes of pseudo-Cushing’s?

A

Alcoholism

Severe Depression

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16
Q

What are the thirteen clinical features associated with Cushing’s syndrome?

A

Moon Face

Central Obesity

Abdominal Striae

Buffalo Hip

Acne Vulgaris

Thin Skin

Hirsutism

Polyuria

Polydipsia

Peripheral Oedema

Low Mood

Decreased Libido

Hypertension

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17
Q

What is buffalo hip?

A

It is defined as the presentation of a fat pad on the patient’s upper back

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18
Q

What are the three specific clincial features associated with Cushing’s disease?

A

Headaches

Visual field defects

Galactorrhea

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19
Q

What are the nine investigations used to diagnose Cushing’s syndrome?

A

Blood Tests

Insulin Tolerance Test

Arterial Blood Gas (ABG)

24-Hour Urinary Free Cortisol

Low Dexamethasone Suppression Test (DST)

High Dexamethasone Suppression Test (DST)

Inferior Petrosal Sinus Sampling (IPSS)

Abdomen CT Scan

Pituitary MRI Scan

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20
Q

What three blood test results indicate Cushing’s syndrome?

A

Increased WCC Levels

Increased Sodium Levels

Decreased Potassium Levels

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21
Q

What underlying cause of Cushing’s syndrome is indicated with hypokalaemia?

A

Paraneoplastic Syndrome

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22
Q

What blood test can be used to identify the underlying cause of Cushing’s syndrome?

A

Serum ACTH

23
Q

What underlying cause of Cushing’s syndrome is indicated by supressed ACTH levels?

A

ACTH independent cause, most commonly an adrenal adenoma

24
Q

What underlying cause of Cushing’s syndrome is indicated by elevated ACTH levels?

A

ACTH dependent cause, most commonly Cushing’s disease (pituatary adenoma)

25
Q

How is an insulin tolerance test used to investigate Cushing’s syndrome?

A

It is used to differentiate between Pseudo-Cushing’s and Cushing’s syndrome

26
Q

What insulin tolerance test reuslt indicates pseudo-Cushing’s?

A

Elevated cortisol levels

27
Q

What insulin tolerance test result indicates Cushing’s syndrome?

A

Suppressed cortisol levels

28
Q

What ABG feature indicates Cushing’s syndrome?

A

Hypokalaemia metabolic alkalosis

29
Q

What is a 24-hour urinary free cortisol?

A

It involves measurement of urinary cortisol levels over a 24 hour period

30
Q

What 24-hour urinary free cortisol result indicates Cushing’s syndrome?

A

Cortisol levels three times the upper limit of normal - > 300mcg

31
Q

What is the gold standard investigation used to diagnose Cushing’s syndrome?

A

Low dexamethasone suppression test (DST)

32
Q

What is the low dexamethasone supression test (DST)?

A

It involves the administration of 1mg of dexamethasone, which is a synthetic glucocorticoid, at night

In the morning, their serum cortisol levels are then measured

33
Q

What is a normal low dexamethasone suppression test result? Explain

A

Decreased cortisol levels

The dexamethasone administration will result in stimulation of the negative feedback system on the hypothalamus and pituitary gland, resulting in decreased secretion of CRH and ACTH levels

Ultimately, this leads to a simultaneous decrease in cortisol levels

34
Q

What low dexamethasone suppression test result indicates Cushing’s syndrome? Explain

A

Elevated serum cortisol levels > 50nmol/L

There is loss of this negative feedback inhibition and therefore serum cortisol levels remain elevated with dexamethasone administration

35
Q

When is the high dexamethasone suppression test (DST) used to investigate Cushing’s syndrome?

A

It is recommended following a positive low dexamethasone suppression test, in order to differentiate between the underlying cause

36
Q

What is the high dexamethasone suppression test (DST)?

A

It involves the administration of 1mg of dexamethasone, which is a synthetic glucocorticoid, at night

In the morning, their serum cortisol and ACTH levels are then measured

37
Q

What high dexamethasone suppression test result indicates Cushing’s syndrome related to Cushing’s disease? Explain

A

Suppressed serum cortisol levels

Suppressed serum ACTH levels

This is due to the fact that dexamethasone administration will result in negative feedback inhibition of the hypothalamus and pituitary gland

38
Q

What high dexamethasone suppression test result indicates Cushing’s syndrome related to an adrenal adenoma? Explain

A

Not suppressed serum cortisol levels

Suppressed serum ACTH levels

This is due to the fact that there is direct excess glucocorticoid secretion from the adrenal glands, and therefore dexamethasone administration will further increase these levels

However, there will be negative feedback inhibition of the hypothalamus and pituitary, so ACTH levels will be suppressed

39
Q

What high dexamethasone suppression test result indicates Cushing’s syndrome related to paraneoplastic syndrome? Explain

A

Not suppressed serum cortisol levels

Not suppressed serum ACTH levels

This is due to the fact that ACTH levels are secreted independent of the hypothalamus-pituitary-adrenal axis, and therefore there will be no negative feedback inhibition of the hypothalamus and pituitary

40
Q

When is inferior petrosal sinus sampling (IPSS) used to investigate Cushing’s syndrome?

A

It is used to differentiate between the underlying cause of Cushing’s syndrome when neuroimaging and high dexamethasone suppression tests are insufficient

41
Q

What is IPSS?

A

It involves sampling veins that drain the pituitary gland, in order to directly measure ACTH levels

These ACTH levels are compared with peripheral ACTH levels, in order to determine whether the Cushing’s syndrome is ACTH-dependent due to a pituitary adenoma

42
Q

What are the two features of Cushing’s syndrome on abdomen CT scan?

A

Adrenal adenomas

Small cell lung cancer

43
Q

What is a feature of Cushing’s syndrome on pituatary MRI scans?

A

Pituitary adenoma

44
Q

What is the management option of exogneous Cushing’s syndrome?

A

We review the patient’s glucocorticoid treatments and alter accordingly – often stopping, reducing or administrating an alternative steroid-sparing immunosuppressive agent

45
Q

What is the pharmacological management option of endogenous Cushing’s syndrome?

A

Glucocorticoid Synthesis Inhibitors

46
Q

When are glucocorticoid synthesis inhibitors used to manage endogenous Cushing’s syndrome?

A

They are used to temporarily reduce glucocorticoid levels, in order to prepare the patient for definitive therapy

In some cases, they can be administered chronically for those who are unfit to undergo definitive surgical management

47
Q

Name three glucocorticoid synthesis inhibitors used to manage endogenous Cushing’s syndrome

A

Ketoconazole

Metyrapone

Mitotane

48
Q

What are the two surgical management options of Cushing’s syndrome?

A

Trans-Sphenoidal Surgery

Laparoscopic Adrenalectomy

49
Q

When is trans-sphenoidal surgery used to manage endogenous Cushing’s syndrome?

A

It is used to manage Cushing’s syndrome related to Cushing’s disease

50
Q

What is trans-sphenoidal surgery?

A

It involves removal of the pituitary adenoma through the sphenoid sinus

51
Q

When is laparoscopic adrenalectomy used to manage endogenous Cushing’s syndrome?

A

It is used to manage Cushing’s syndrome related to adrenal adenomas

52
Q

What is laparoscpic adrenalectomy?

A

It involves laparoscopic removal of the adrenal tumour

53
Q

In cases of bilateral adrenalectomy, what pharmaoclogical management option should be administered?

A

Immediate steroid replacement therapy

54
Q

What are the six complications of Cushing’s syndrome?

A

Hypertension

Heart Failure

Type Two Diabetes Mellitus

Obesity

Metabolic Syndrome

Osteoporosis

Year Two - Endocrine System (17 decks)

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