HPA axis - clinical aspects Flashcards

1
Q

How is cholesterol mobilised into the adrenal cortex?

A

Via activation of ACTH

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2
Q

In the adrenal medulla, what is cholesterol covered into?

A

Either Aldosterone, Cortisol or Androgens

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3
Q

Which hormone helps the conversion of cholesterol into aldosterone?

A

Angiotensin II

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4
Q

Which hormones maintain homeostasis during stress (bleeding, infection, etc)?

A

Glucocorticoids

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5
Q

What are the main affects of glucocorticoids?

A

Maintain homeostasis
Anti-inflammatory
Energy balance/metabolism
Form bone + cartilage
Regulate blood pressure
Cognitive function, memory, conditioning

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6
Q

What two dynamic tests can be done to assess the adrenal axis?

A

Stimulation to check for deficit - synacthen, glucagon stimulation, insulin stress test
Suppression to check for excess - ONDST, LDDST, HDDST

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7
Q

What are the two types of Cushing’s syndrome?

A

ACTH dependent Cushings
ACTH Independent Cushings

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8
Q

What causes ACTH Dependent Cushing’s syndrome? Would the ACTH level be high or low?

A

Pituitary tumour
Ectopic ACTH secretion
High ACTH level

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9
Q

What causes ACTH Independent Cushing’s syndrome? Would the ACTH level be high or low?

A

Adrenal tumour
Long term steroid therapy
Low ACTH level

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10
Q

What signs and symptoms do patients present with, in glucocorticoid excess?

A
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11
Q

Pigmentation occurs in which type of Cushings and why?

A

ACTH Dependent Cushing’s syndrome.
Occurs due to high ACTH levels.

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12
Q

What is the preferred testing method for glucocorticoid excess?

A

Overnight dexamethasone test

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13
Q

If cortisol can be suppressed on a low dose dexamethasone test, is the glucocorticoid excess caused by the adrenal or pituitary gland?

A

Adrenal

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14
Q

If cortisol can be suppressed on a high dose dexamethasone test, is the glucocorticoid excess caused by the adrenal or pituitary gland?

A

Pituitary

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15
Q

Which type of imaging should be done if a pituitary cause is suspected in glucocorticoid excess?

A

MRI

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16
Q

In adrenal imaging, when would a malignancy be suspected?

A

> 4cm
Heterogenous = calcification and necrosis
Extending out of capsule = invasive

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17
Q

What medications can be used to treat glucocorticoid excess?

A

Adrenal gland - Ketoconazole. Mifepristone (approved for those with cushings + T2DM).
Pituitary - Somatostatin analogues or dopamine agonist therapy.

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18
Q

What types of surgery can treat glucocorticoid excess?

A

Transsphenoidal adenectomy
Adrenalectomy

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19
Q

What are the two types of glucocorticoid deficiency?

A

Primary adrenal insufficiency
Secondary adrenal insufficiency

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20
Q

What can cause both primary and secondary adrenal insufficiency?

A

Autoimmune conditions
Infiltrative e.g. sarcoidosis
Infections e.g. TB, Fungal, AIDS
Vascular e.g. haemorrhage/infarction
Drugs
Metastatic deposition

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21
Q

What causes are specific to primary adrenal insufficiency?

A

CAH - Congenital Adrenal Hyperplasia
Adrenoleucodystrophy

22
Q

Can head trauma cause primary or secondary adrenal insufficiency?

A

Secondary

23
Q

Is there both glucocorticoid and mineralocorticoid deficiency in primary and secondary adrenal insufficiency?

A

No, both in primary.
Glucocorticoid deficiency only in secondary.

24
Q

What is the most common cause of primary adrenal insufficiency?

A

Autoimmune adrenalitis

25
Q

Which antibody is associated with autoimmune adrenalitis?

A

21- hydroxylase

26
Q

What age does primary adrenal insufficiency typically occur at?

A

30-50 years

27
Q

How much of the Adrenal cortex is destroyed before symptoms of primary adrenal insufficiency occur?

A

90%

28
Q

What is the MOA of ketoconazole?

A

Decreases cortisol synthesis.

29
Q

What is the MOA of Rifampicin?

A

Increases cortisol metabolism.

30
Q

Which drugs can cause glucocorticoid insufficiency?

A

Ketoconazole
Rifampicin

31
Q

What are the clinical features of adrenal insufficiency?

A
32
Q

Pigmentation of the skin occurs in what type of adrenal insufficiency and why?

A

Primary.
Increased ACTH due to reduced cortisol levels. ACTH and Melanocytes have the same precursor molecule.

33
Q

What is the difference between primary and secondary adrenal insufficiency?

A

Primary - Adrenal glands don’t make enough cortisol and aldosterone despite a normal/increased ACTH.
Secondary - Pituitary gland doesn’t make enough ACTH. ACTH controls the production of cortisol. Less ACTH = Less cortisol.

34
Q

What tests can be done to diagnose adrenal insufficiency?

A

9am cortisol
ACTH levels
Na+, K+, pH
Renin (high), Aldosterone (Low)
Adrenal antibodies

35
Q

What is the dynamic testing used to confirm adrenal insufficiency and how is this done?

A

Synacthen test.
Synthetic ACTH at 9am. Measure Cortisol at 0, 30 and 60 minutes.
Beware of steroids + only do if equivalent of 5mg prednisolone or less + omit on morning of test.

36
Q

What does it mean if the levels of cortisol 30minutes post synacthen test are >420nmol/L?

A

No adrenal insufficiency as cortisol is being produced from the ACTH.

37
Q

What does it mean if the levels of cortisol 30minutes post synacthen test are <420nmol/L, but >420nmol/L at 60minutes?

A

A slow/delayed adrenal response.

38
Q

What is adrenal crisis?

A

An emergency caused by a lack of cortisol.

39
Q

What is the management of adrenal crisis?

A

IV Hydrocortisone
IVI
Hypoglycaemic management
Mineralocorticoid replacement once daily glucocorticoid dose <50mg/24hours (primary adrenal insufficiency only). - Fludrocortisone 100mcg OD.

40
Q

What is the long term management of adrenal crisis?

A

Replacement - steroids. Mineralocorticoid if primary.
Education.
Home emergency hydrocortisone injection.
Steroid card

41
Q

What are the sick day rules in adrenal insufficiency?

A

Moderate illness (fever, infection etc) - Double daily steroid dose.
Severe illness (vomiting GI illness, surgery, colonoscopy prep) - IV Hydrocortisone 100mg then 200mg/24hours. OR IM Hydrocortisone 100mg then 50mg every 60 hours.

42
Q

How does exogenous steroids affect the adrenal cortex?

A

Causes atrophy of zona fasciculate and zona reticularis.
Zona glomerulose spared due to RAAS.

43
Q

What is the equivalent dose of Prednisolone 5mg into Hydrocortisone and Dexamethasone?

A
44
Q

What is autoimmune polyglandular syndrome?

A

Deficiencies in the function of several endocrine glands.
Circulating autoantibodies and lymphocytic filtration of the affected multiple tissues.

45
Q

In autoimmune polyglandular syndrome, which conditions may occur together?

A
46
Q

What are the four types of autoimmune polyglandular syndromes?

A
47
Q

If someone with T1DM presents with weight loss, hypoglycaemia and fatigue, what should be checked?

A

9am cortisol

48
Q

If someone with T1DM presents with Gi symptoms, what should be checked?

A

Markers for coeliac disease.

49
Q

If someone with T1DM also has Addison’s disease, what should be checked?

A

TFTs
Coeliac screen

50
Q

What should be asked when taking an endocrine history?

A
51
Q

What should be examined in an endocrine examination?

A