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Endocrinology > Adrenal disorders > Flashcards

Adrenal disorders Flashcards

1
Q

What is a steroid?

A

A hormone derived from cholesterol

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2
Q

What hormones are made in the adrenal cortex?

A

Corticosteroids:
Mineralocorticoids (Aldosterone)
Glucocorticoids (Cortisol)
Sex steroids (Androgens, oestrogens)

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3
Q

What effect does angiotensin II have on the adrenals?

A

increases aldosterone production

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4
Q

What is the role of aloesterone?

A

Controls blood pressure: keeps sodium in and lowers/ pushes out potassium

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5
Q

What are the effects of ACTH on the adrenals?

A

ACTH stimulates the production of cortisol (blood glucose controlling hormone)

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6
Q

What is an enzyme?

A

Protein that catalyses a specific reaction

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7
Q

Describe how aldosterone is made?

A
  1. Cholesterol ->
  2. progesterone ->
  3. converted into 11-deoxycorticosterone via 21 hydroxylase
  4. converted into corticosterone via 11hydroxylase
  5. converted into aldosterone via 18 hydroxylase
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8
Q

Describe how cortisol is made?

A
  1. Cholesterol ->
  2. Progesterone ->
  3. Converted into 17- OH progesterone via 17- hydroxylase
  4. converted into 11-deoxycortisol via 21- hydroxylase
  5. Converted into cortisol via 11- hydroxylase
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9
Q

Describe how oestrogen is made?

A
  1. Cholesterol ->
  2. Progesterone ->
  3. Converted into 17- OH progesterone via 17- hydroxylase
  4. converted into sex steroids->
  5. androgens ->
  6. oestrogen
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10
Q

What is addison’s disease?

A
  1. Primary adrenal failure
  2. Autoimmune disease where the immune
    system decides to destroy the adrenal
    cortex (UK)
  3. Tuberculosis of the adrenal glands
    (commonest cause worldwide)
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11
Q

Describe the pattern of cortisol release in the body? what is the clinical significance of this pattern?

A
  • Cortisal had diurnal rhythm- peaks at 8:32 am
  • Blood samples are usually taken twice during the day, once in the morning when cortisol levels are at their highest
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12
Q

What is addison’s disease

A
  • Primary adrenal failure
  • Autoimmune disease where the immune system decides to destroy the adrenal cortex
    (commonly caused by TB)
  • Pituitary starts secreting lots of ACTH and hence MSH ( they have the same precursor)
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13
Q

What are the symptoms of Addison’s disease?

A

Adrenal crisis:
- fever
- syncope (fainting)
- convulsions (seizures)
- Hypoglycemia
- Hyponatremia (low Na+)
- Severe vomiting diarrhoea
- Hyperpigmentation
- low blood pressure (no cortisol/ aldosterone)
- weakness
- weight loss
- Nausea
- Diarrhea
- Vomiting
- Constipation
- Abdominal pain
- Vitiligo

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14
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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15
Q

What are the causes of adrenocortical failure?

A

*Tuberculous Addison’s disease
(commonest worldwide)
*Autoimmune Addison’s disease
(commonest in UK)
*Congenital adrenal hyperplasia

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16
Q

What are the consequences of adrenocortical failure

A

*Fall in blood pressure
*Loss of salt in the urine
*Increased plasma potassium
*Fall in glucose due to glucocorticoid
deficiency
*High ACTH resulting in increased
pigmentation (high ACTH= high MSH; same precursor)

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17
Q

How would you test for Addison’s

A

*9am cortisol = low
*ACTH = high
*Short synACTHen test
*Give 250 ug synacthen IM (injection)
*Measure cortisol response

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18
Q

What is the treatment for adrenal failure?

A

*Hydrocortisone three times daily (10 + 5 + 2.5)
*Prednisolone 3mg daily
*Fludrocortisone 50 to 100 mcg daily

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19
Q

Why is fludrocortisone given to treat Adisson’s disease (as opposed to aldosterone or cortisol)

A
  • Half life of aldosterone is too short for safe once daily administration
  • Fluorine does not exist in natural steroids, so its presence slows metabolism substantially.
  • Binds to both MR and GR
  • Fludrocortisone half life 3.5h and
    effects seen for 18h.
20
Q

What is congenital adrenal hyperplasia?

A

-Enzyme deficiency
-Can be complete or partial

21
Q

What are the consequences of complete 21-hydroxylase deficiency

A

*Which hormones will be totally absent?:
aldosterone and cortisol
*How long can you survive ?
Less than 24 hours
*Which hormones will be in excess?
Sex steroids and testosterone
*Girls might have ambiguous
genitalia (virilised by adrenal testo)
-boys look normal- hard to predict they’re having a crisis- might not be put on saline- v. dangerous

22
Q

What is the age of presentation of complete 21-hydroxylase deficiency

A

*As a neonate with a salt losing
Addisonian crisis
*Before birth, (while in utero),
foetus gets steroids across placenta

23
Q

What are the consequences of partial 21 hydroxylase deficiency

A

*Partial 21 hydroxylase deficiency means that there will be a bit of aldosterone and cortisol to get by with- so no crisis
*Which hormones are in excess ?
*Sex steroids and testosterone
*Main problem in later life is
hirsutism and virilisation in girls
and precocious puberty in boys due
to adrenal testosterone

24
Q

What is the age of presentation of partial 21-hydroxylase deficiency

A

*At what age will they present ?
*Any age as they survive

25
Q

What are the consequences of 11 hydroxylase deficiency?

A

-No cortisol or aldosterone
-But 11 deoxycorticosterone is, thereofore, in excess
-11 deoxycorticosterone acts like aldosterone- no crisis is caused
-but can cause hypertension and hypokalaemia
*Which hormones are in excess ?
*Sex steroids and testosterone and 11-
deoxycorticosterone
*Problems :
*Virilisation, hypertension and low K

26
Q

What are the consequences of 17 hydroxylase deficiency?

A

*Which hormones are deficient ?
*Cortisol and sex steroids
*Which hormones are in excess ?
*11-deoxycorticosterone and aldosterone
(mineralocorticoids)
*Problems :
* Hypertension, low K, sex steroid deficiency
and glucocorticoid deficiency (lo7w glucose).

27
Q

What is Cushing’s syndrome?

A

Cushing’s syndrome is a condition caused by having too much of a hormone called cortisol in your body

28
Q

What are the clinical features of Cushing’s?

A

Too much cortisol
Centripetal obesity
Moon face and buffalo hump
Proximal myopathy
Hypertension and hypokalaemia
Red striae, thin skin and bruising
osteoporosis, diabetes

29
Q

List the causes of Cushing’s

A

Taking too many steroids
- Pituitary dependent Cushing’s disease
- Ectopic ACTH from lung cancer
- adrenal adenoma secreting cortisol

30
Q

What investigations are used to determine the cause of Cushing’s syndrome

A

*24 h urine collection for urinary free cortisol
*Blood diurnal cortisol levels
*Low dose dexamethasone suppression test:
- 0.5 mg 6 hourly for 48 hrs
- Dexamethasone = artificial steroid
- Normals will suppress cortisol to zero
- Any cause of Cushing’s will fail to
suppress

31
Q

What is reading’s are needed to diagnose Cushing’s?

A

Basal (9am) cortisol 800 nM
End of LDDST (Low dose dexamethasone suppression test:): 680 nM

32
Q

What is the “Low dose dexamethasone suppression test”?

A
  • can help tell whether your body is producing too much ACTH
  • Dexamethasone is a man-made (synthetic) steroid that binds to the same receptor as cortisol.
  • Dexamethasone reduces ACTH release in normal people.
  • Therefore, taking dexamethasone should reduce ACTH level and lead to a decreased cortisol level.
  • If your pituitary gland produces too much ACTH, you will have an abnormal response to the low-dose test. But you can have a normal response to the high-dose test.
33
Q

What is the action of the drug “Metyrapone”?

A

(drug used to treat Cushing’s= XS cortisol)
- inhibition of 11b-hydroxylase
- steroid synthesis in the zona fasciculata [and reticularis] is arrested at the 11-deoxycortisol stage
- Therefore, production of cortisol and corticosterone is inhibited
- 11-deoxycortisol has no negative feedback effect on the hypothalamus and pituitary gland.

34
Q

What are the uses of Metyrapone?

A
  1. Control of Cushing’s syndrome prior to surgery.
    - adjust dose (oral) 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)
  2. Control of Cushing’s symptoms after radiotherapy (which is usually slow to take effect)
35
Q

What are the side effects of using Metyrapone?

A
  1. Hypertension on long-term administration
    - Inhibition of 11b-hydroxylase; more precursor can be used in other pathways of the cholesterol/ steroid
    - Therefore deoxycorticosterone (product that is usually broken down by enzyme 11) accumulates in z. glomerulosa; it has aldosterone-like (mineralocorticoid) activity, leading to salt retention and hypertension.
  2. Hirsutism
    - There is also increased adrenal androgen production= HIRSUTISM in women
36
Q

What is the action of Ketoconazole?

A
  • Similar to metyrapone
  • used to treat Cushings: treatment and control of symptoms prior to surgery
  • Mainly blocks 17a hydroxylase, inhibiting cortisol production
  • orally active
37
Q

What are the side effects of ketoconazole?

A

Liver damage - possibly fatal - monitor liver function weekly, clinically and biochemically

38
Q

What is the treatment of Cushing’s?

A

Depends on cause
surgical treatment:
Pituitary surgery (transsphenoidal hypophysectomy)
Bilateral adrenalectomy
Unilateral adrenalectomy for adrenal mass
Medical treatment:
Metyrapone
Ketoconazole

39
Q

What is Conn’s syndrome?

A

Benign adrenal cortical tumour (zona glomerulosa)
Aldosterone in excess
Hypertension and hypokalaemia

40
Q

What is the role of aldosterone?

A

Controls blood pressure, sodium and lowers potassium

41
Q

What criteria must be met for a Conn’s syndrome diagnosis?

A

Primary hyperaldosteronism

Renin - angiotensin system should be suppressed (exclude secondary hyperaldosteronism)

42
Q

What is the action of Spironolactone?

A
  1. Drug used to treat Primary hyperaldosteronism (Conn’s syndrome)
  2. Converted to several active metabolites, including canrenone, a competitive antagonist of the mineralocorticoid receptor (MR).
  3. Mineralocorticoid receptors (MR) bind both mineralocorticoids and glucocorticoids with high affinity (deoxycorticosterone = corticosterone >/= aldosterone = cortisol)
  4. Blocks Na+ resorption and K+ excretion in the kidney tubules (potassium sparing diuretic).
    - Orally active
    - Highly protein bound and metabolised in the liver
43
Q

What are the side effects of Spironolactone?

A

Menstrual irregularities (+ progesterone receptor)
Gynaecomastia: condition that causes boys’ and men’s breasts to swell and become larger (- androgen receptor)

44
Q

What is the action of Epleronone?

A
  • A mineralocorticoid receptor (MR) antagonist
  • Mineralocorticoid receptors (MR) bind both mineralocorticoids and glucocorticoids with high affinity (deoxycorticosterone = corticosterone >/= aldosterone = cortisol)
  • Similar affinity to the MR compared to spironolactone
  • Less binding to androgen and progesterone receptors compared to spironolactone, so better tolerated
45
Q

What are Phaeochromocytomas?

A

These are tumours of the adrenal MEDULLA which secrete catecholamines
(adrenaline and nor-adrenaline)
- 10 % extra-adrenal (sympathetic chain)
- 10 % malignant
- 10 % bilateral
- Phaeo’s are extremely rare

46
Q

What are the clinical features of Phaeochromocytomas?

A
  • Hypertension in young people
  • Episodic severe hypertension (after abdominal palpation)
  • More common in certain inherited conditions
  • Severe hypertension can cause myocardial infarction or stroke
  • High adrenaline can cause ventricular fibrillation + death
  • Thus this is a medical emergency
47
Q

How are Phaeochromocytomas managed?

A
  • Alpha blockade is first therapeutic step.
  • Patients may need intravenous fluid as alpha blockade commences
  • Beta blockade added to prevent tachycardia
  • Eventually need surgery, but patient needs careful preparation as anaesthetic can precipitate a hypertensive crisis

Endocrinology (14 decks)

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