Addison's disease (E&M) Flashcards

1
Q

What is Addison’s disease?

A

Primary adrenal insufficiency - destruction of adrenal cortex –> decreased production of adrenocortical hormones - glucocorticoids (cortisol) and mineralocorticoids (aldosterone)

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2
Q

What are the main steroids that are deficient in Addison’s disease? (3)

A
  • cortisol
  • aldosterone
  • dehydroepiandrosterone (DHEA) + sulfated conjugate (DHEA-S)
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3
Q

What is Addison’s disease the commonest cause of?

A

Adrenocortical failure in the UK

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4
Q

What are the main causes of Addison’s disease? (3+3)

A
  • autoimmune (more developed countries)
  • tuberculosis (more common worldwide)
  • metastases
  • (meningococcal septicaemia –> Waterhouse-Friderichsen syndrome)
  • (HIV)
  • (antiphospholipid syndrome)
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5
Q

What are some risk factors for Addison’s disease? (8)

A
  • female sex
  • adrenocortical antibodies
  • adrenal haemorrhage
  • autoimmune diseases
  • coeliac disease
  • TB/non-TB infection
  • sarcoidosis
  • anticoagulant use
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6
Q

What is an Addisonian crisis?

A

A sudden worsening of symptoms and drop in cortisol levels, caused by:

  • sudden withdrawal of steroids if patient on long-term steroids
  • sepsis
  • surgery
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7
Q

What are the clinical features of Addison’s disease? (7)

A
  • fatigue
  • anorexia
  • weight loss
  • hyperpigmentation (low cortisol = increased ACTH –> increased POMC –> increased a-MSH)
  • nausea, vomiting, abdominal pain
  • postural hypotension
  • hypoglycaemia –> dizziness
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8
Q

What might you see on examination in Addison’s disease? (2)

A
  • hyperpigmentation - exaggerated over pressure points on elbows, area of buccal hyperpigmentation where teeth pinch mucous membrane while chewing
  • hypotension (can be postural)
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9
Q

Why does hyperpigmentation occur in Addison’s disease?

A

Low cortisol –> negative feedback increases ACTH –> increased POMC –> increased alpha-MSH

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10
Q

What are the features of an Addisonian crisis? (2)

A

Severe hypovolaemia and hyponatraemia

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11
Q

What are the first-line investigations for Addison’s disease?

A
  • ACTH stimulation test (short synACTHen test)
  • morning serum cortisol
  • plasma ACTH
  • serum electrolytes
  • U&Es
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12
Q

What is the definite investigation done in Addison’s disease?

A

ACTH stimulation test (short synACTHen test):

  • plasma cortisol measured before and 30min after giving Synacthen 250mg IM
  • Synacthen should stimulate cortisol secretion but does not happen in Addison’s disease
  • serum cortisol <550nmol/L indicates adrenal failure
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13
Q

When do we do morning serum cortisol for Addison’s disease?

A
  • done if short Synacthen test is unavailable e.g. in primary care
  • 9am blood test (cortisol peaks in morning) - if low, suspect Addison’s disease
  • > 500nmol/L = very unlikely
  • 100-500nmol/L = prompt ACTH stimulation test
  • <100nmol/L = definitely abnormal
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14
Q

What electrolyte abnormalities might be seen in Addison’s disease (1/3 undiagnosed patients)? (3)

A
  • hyperkalaemia
  • hyponatraemia
  • hypoglycaemia
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15
Q

What might we see on ABG in Addison’s disease?

A

Metabolic acidosis with normal anion gap

Anion gap = (Na + K) - (HCO3 + Cl)
Normal = 8-14mmol/L

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16
Q

What do we look for in FBC in Addison’s disease?

A

Anaemia and eosinophilia in some

17
Q

What are some differential diagnoses for Addison’s disease? (7)

A
  • adrenal suppression due to corticosteroid therapy (low ACTH due to suppression)
  • secondary/tertiary adrenal insufficiency (pituitary/brain lesion, low ACTH and other pituitary hormones)
  • haemochromatosis
  • hyperthyroidism
  • occult malignancy
  • anorexia nervosa
  • SIADH
18
Q

How do we manage stable patients with Addison’s disease?

A

Lifelong glucocorticoid + mineralocorticoid replacement:
Hydrocortisone given in 2/3 divided doses (glucocorticoid) + fludrocortisone (mineralocorticoid)

19
Q

When are hydrocortisone doses given (Addison’s disease)?

A

Majority given at start of first half of day and rest given in second half (2/3 doses per day –> 20-30mg)

20
Q

What do we have to ensure if patient with Addison’s disease also has hypothyroidism?

A

Give hydrocortisone BEFORE thyroxine (to prevent precipitating an Addisonian crisis)

21
Q

How does Addison’s disease treatment change during intercurrent illness?

A

Hydrocortisone dose doubled, fludrocortisone dose stays the same

(If severe intercurrent stress - IV hydrocortisone - stress dose)

22
Q

How do we manage an Addisonian crisis? (3)

A
  • IV hydrocortisone (100mg bolus)
    • followed by 50mg every 6h until stable
    • fludrocortisone not needed as high cortisol exerts weak mineralocorticoid action
    • oral replacement after 24h and tapered to maintenance doses over 3-4d
  • rapid IV fluid resuscitation
  • glucose (50mL of 50% dextrose) - hypoglycaemia
23
Q

What are some complications of Addison’s disease? (4)

A
  • secondary Cushing’s syndrome (over-replacement)
  • osteopenia/osteoporosis (over-replacement, decrease glucocorticoid if no other cause)
  • treatment-related hypertension (over-replacement –> mineralocorticoid hypertension and hypokalaemia)
  • Nelson’s syndrome (rapid enlargement of a pre-existing corticotroph adenoma after bilateral adrenalectomy due to severe Cushing’s)