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endo > 1B adrenal disorders > Flashcards

1B adrenal disorders Flashcards

1
Q

What is Addison’s disease?

A
  • Primary adrenal failure- an autoimmune disease where the immune system decides to destroy the adrenal cortex
    (UK)
  • Autoimmune skin condition vitiligo may coexist
  • No cortisol or aldosterone so low bp
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2
Q

What does the pituitary do to deal with primary adrenal failure and what consequence therefore follows?

A

Starts secreting a lot more ACTH and hence MSH therefore causing increased pigmentation

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3
Q

What is the commonest cause of Addison’s worldwide?

A

Tuberculosis

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4
Q

What are the tests for Addison’s disease?

A
  • Morning 9am cortisol and ACTH. If cortisol is low and ACTH is high then we know its Addison’s
  • Short synACTHen test where you do cortisol blood test and then give 250μg synacthen IM and measure cortisol response- if little response then we know its Addison’s
  • Clinical suspicion: Hyponatraemia + hyperkalaemia and fatigue
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5
Q

Why do patients with Addison’s disease have a good tan?

A

POMC is a large precursor protein that is cleaved to form a number of smaller peptides, including ACTH, MSH and endorphins.

Thus people who have pathologically high levels of ACTH may become tanned.

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6
Q

What are the consequences of adrenocortical failure?

A
  • Fall in bp (postural hypotension)
  • Loss of salt in urine (low sodium in plasma = hyponatraemia)
  • Increased plasma potassium (less potassium excreted in urine = hyperkalaemia)
  • Fall in glucose due to glucocorticoid deficiency
  • High ACTH resulting in increased pigmentation
  • Eventual death due to severe hypotension
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7
Q

What is the aldosterone treatment for Addison’s?

A

Aldosterone replacement

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8
Q

What is the issue with the standard treatment for Addison’s?

A

Half life of aldosterone is too short for safe once daily administration

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9
Q

How is the issue with Aldosterone’s half life fixed?

A
  • Solve this by sticking a fluorine on aldosterone to make fludrocortisone (F doesn’t exist in natural steroids so its presence slows down its metabolism a lot so it stays active for longer)
  • Fludrocortisone binds to both MR (mineralocorticoid) and GR (glucocorticoid) receptors
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10
Q

How much fludrocortisone is administered?

A

Usually give 50-100μg daily

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11
Q

What is the issue with hydrocortisone and how do we fix it?

A
  • Oral hydrocortisone has a short half life- too short for once daily administration
  • We give it 2 or 3 times daily because of this
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12
Q

What further problems of hydrocortisone are there?

A
  • Late peaks are harmful
  • We need a longer lasting version that we can take once and smoothly and slowly decreases across the day
  • If we add a double bond to hydrocortisol we get 1-2 dehydrohydrocortisone aka prednisolone
  • This has a longer half life and is more potent than cortisol with 2.3x the binding affinity of cortisol
  • Prednisolone is taken 2-4mg once daily (which is equivalent to 15-25mg of hydrocortisone per day)
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13
Q

What doses of prednisolone are available?

A
  • 1mg, 2.5mg, 5mg
  • Not enteric coated which slows absorption but avoids side effects

Treatment for Addison’s

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14
Q

What is the treatment of adrenal failure then altogether?

A
  • Fludrocortisone 50-100μg daily
  • Either hydrocortisone 3 times daily (10mg morning, 5mg afternoon, 2.5mg evening) or prednisolone 3mg daily
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15
Q

What is Congenital Adrenal Hyperplasia the third cause of and what are the other 2 causes?

A
  • 3rd cause of primary adrenal failure
  • Other 2 are TB Addison’s disease (commonest worldwide) and autoimmune Addison’s disease (commonest in UK)
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16
Q

What is the commonest cause of CAH?

A
  • 21-hydroxylase deficiency
  • Can be complete or partial deficiency
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17
Q

Which hormones will be totally absent in complete 21 hydroxylase deficiency/ classical CAH?

A

Aldosterone and cortisol

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18
Q

How long can a patient survive with classical CAH?

A

Less than 24 hours. Babies present within 1-3 weeks with a salt-losing crisis

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19
Q

Which hormones will be in excess in classical CAH?

A

Sex steroids and testosterone

Less of a problem if with male baby because there are lots of testosterone anyway.

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20
Q

What is the age of presentation for classical CAH?

A
  • As a neonate, with a salt losing Addisonian crisis
  • Before birth (in utero) the foetus gets steroids across the placenta
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21
Q

What is the difference between how girls and boys present in classical CAH?

A

Girls might have ambiguous genitalia (virilised by adrenal testosterone) but boys aren’t

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22
Q

What happens in partial 21 hydroxylase deficiency (aka non-classical CAH)?

A

There is still a bit of aldosterone and cortisol to get by with

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23
Q

Which hormones are deficient in partial 21 hydroxylase deficiency (aka non-classical CAH)?

A

Cortisol and aldosterone

24
Q

Which hormones are in excess in non-classical CAH?

A

Sex steroids and testosterone

25
At what age will a patient present with non-classical CAH?
Any age as they survive
26
What is the main problem for girls and boys in non-classical CAH?
- Girls- hirsutism and virilisation - Boys- precocious puberty due to adrenal testosterone
27
What happens if we have 11 hydroxylase deficiency?
- There's a build up of 11 deoxycorticosterone - This behaves like aldosterone and the excess of it means it can cause hypertension and hypokalaemia
28
Which hormones are deficient in 11 hydroxylase deficiency?
Cortisol and aldosterone
29
Which hormones are in excess in 11 hydroxylase deficiency?
Sex steroids, testosterone and 11-deoxycorticosterone
30
What problems present with 11 hydroxylase deficiency?
- Virilisation - Hypertension - Low K
31
Which hormones are deficient in 17 hydroxylase deficiency?
Cortisol and sex steroids
32
Which hormones are in excess in 17 hydroxylase deficiency?
11-deoxycorticosterone and aldosterone (mineralocorticoids)
33
What problems does 17 hydroxylase deficiency cause?
- Hypertension - Hypokalaemia - Sex steroid deficiency - Glucocorticoid deficiency (low glucose)
34
What are the clinical features of Cushing's syndrome?
- Too much cortisol - Centripetal obesity (cortisol drives protein to be broken down and fat to be synthesised) - Moon face and buffalo hump - Proximal myopathy - Hypertension and hypokalaemia - Red striae, thin skin and bruising - Osteoporosis, diabetes
35
What is the difference between Cushing's disease and syndrome?
- Cushing's syndrome is excess cortisol in body - Cushing's disease is a type of Cushing's syndrome where there's a pituitary tumour causing excess cortisol
36
How does the dexamethasone test work?
- It's a very potent artificial steroid - we give 0.5mg every 6 hours for 48 hours - Normal patients' pituitary will respond via negative feedback (thinks its cortisol) and decrease cortisol production to 0 - **Any** cause of Cushing's will fail to suppress the cortisol production
37
What is the diagnosis of Cushing's?
- Basal (9am) cortisol 800nM - End of LDDST: 680nM
38
What is metyrapone and what action does it have?
- Inhibition of 11beta-hydroxylase - Steroid synthesis in zona fasciculata (and reticularis) is therefore arrested at the 11-deoxycortisol stage - 11-deoxycortisol has no negative feedback effect on the hypothalamus and pituitary gland (pituitary keeps on making ACTH)
39
How is metyrapone used and what for?
- Adjust metyrapone oral dose according to cortisol (aim for mean serum cortisol 150-300 nmol/L) - Improves patient's symptoms and promotes better post-op recovery (better wound healing, less infection etc) - Used to control Cushing's symptoms **prior to surgery** and also after radiotherapy (which is usually slow to take effect)
40
What does the accumulation of **11-deoxycorticosterone** in the zona glomerulosa do?
Has aldosterone-like (mineralocorticoid) activity, leading to salt retention (hypokalaemia) and hypertension
41
What does increased adrenal androgen production do?
Causes hirsutism in women
42
What action does ketoconazole have?
- Mainly blocks 17alpha hydroxylase, inhibiting cortisol production - Main use is as an antifungal agent- although withdrawn in 2013 due to risk of hepatotoxicity - At higher conc, inhibits steroidogenesis
43
What is ketoconazole used for?
- Treatment and control of symptoms prior to surgery - Orally active
44
What is an unwanted side effect of ketoconazole?
- Liver damage- possibly fatal - Monitor liver function weekly, clinically and biochemically
45
What are the other treatments of Cushing's
Depends on cause - Pituitary surgery (transsphenoidal hypophysectomy) - Bilateral adrenalectomy - Unilateral adrenalectomy for adrenal mass
46
What is Conn's syndrome?
- Benign adrenal cortical tumour (zona glomerulosa) - Aldosterone in excess (aldosterone controls bp, Na and lowers K remember) - Hypertension and hypokalaemia
47
How do we diagnose Conn's syndrome?
- It's primary hyperaldosteronism - The renin-angiotensin system should be suppressed (exclude secondary hyperaldosteronism)
48
What drugs are used to treat Conn's syndrome?
Use an MR antagonist: - Spironolactone - Eplerenone
49
What does spironolactone do?
- Converted to several active metabolites in body, including canrenone, a competitive antagonist of the mineralocorticoid receptor (MR) - Blocks Na+ resorption and K+ excretion in the kidney tubules (potassium sparing diuretic)
50
What are some unwanted side effects of spironolactone?
- Menstrual irregularities (agonist for progesterone receptor) - Gynaecomastia (blocks androgen receptor)
51
What does eplerenone do?
- Also an MR antagonist - Similar affinity to the MR compared to spironolactone - Less binding to androgen and progesterone receptors compared to spironolactone, so better tolerated
52
What is a phaeochromocytoma?
These are tumours of the **adrenal medulla** which secrete catecholamines (adrenaline and noradrenaline)
53
What are clinical features of a phaeo?
- Hypertension in young people- severe hypertension can cause myocardial infarction or stroke - Episodic severe hypertension (after abdominal palpitation) - High adrenaline can cause ventricular fibrillation & death- it's a medical emergency - More common in certain inherited conditions
54
What is the management of phaeo?
- Eventually need surgery, but patient needs careful prep as anaesthetic can precipitate a hypertensive crisis - **Alpha blockade** is the first therapeutic step to block adrenaline effects for surgery - Patients may need **intravenous fluid** as alpha blockade commences (because blockade causes blood pressure crash so we need the fluid) - **Beta blockade added** to prevent tachycardia
55
Key facts about phaeos
- They're extremely rare - 10% of them are extra-adrenal (sympathetic chain) - 10% are malignant - 10% are bilateral

endo (12 decks)

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