Adrenal Flashcards

1
Q

What type of molecules are mineralocorticoids, glucocorticoids and androgens?

A

Steroids.

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2
Q

What is the precursor for steroids?

A

Cholesterol.

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3
Q

How is adrenal steroidogenesis analogous to the story of Adam and Eve?

A

Female sex hormones are made from adrenal hormones, which are male sex hormones.

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4
Q

What is congenital adrenal hyperplasia (CAH)?

A

A group of autosomal recessive disorders characterized by a deficiency of mineralocorticoids and glucocorticoids.

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5
Q

Which molecule is most commonly deficient in congenital adrenal hyperplasia?

A

21-hydroxylase.

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6
Q

Which gene produces 21-hydroxylase?

A

CYP21A2.

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7
Q

Why does congenital adrenal hyperplasia cause high sex steroid hormone levels?

A
  • There is no negative feedback from mineralocorticoids or glucocorticoids as they are no longer produced.
  • This increases the level of ACTH in the blood.
  • The adrenals respond by increasing sex steroid hormone production.
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8
Q

List 3 consequences of congenital adrenal hyperplasia (other than changes in hormone levels).

A

1 - The adrenal glands become hyperplastic.

2 - Newborn girls with the condition are virilised (a condition known as 46,XX disorder of sex development) as they are producing male sex hormones (androgens).

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9
Q

Which molecules build up as a result of 21-hydroxylase deficiency?

What is the function of these molecules?

What happens to these molecules?

A
  • Progesterone and 17-hydroxyprogesterone.
  • These are precursors to mineralocorticoids and glucocorticoids respectively
  • Progesterone is converted into 17-hydroxyprogesterone, which is then converted into androstenedione, a sex hormone precursor.
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10
Q

Which molecule, when in excess, is used as an indicator of 21-hydroxylase deficiency?

A

17-hydroxyprogesterone.

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11
Q

What is the prader scale?

A
  • A rating system of 0-5 for the measurement of the degree of virilisation of the genitalia.
  • More female characteristics lean towards 0, whereas more male characteristics lean towards 5.
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12
Q

What anatomical abnormality occurs at Prader stage 5?

A

The vagina and urethra form a common duct.

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13
Q

Why do more males die from congenital adrenal hyperplasia than females?

A
  • Congenital adrenal hyperplasia causes excessively high androgen production.
  • Since these are male sex hormones, females with the condition are more easy to identify as the female genitalia is virilised, whereas the male genitalia is unchanged.
  • More males are therefore undiagnosed at birth and die from losing the functions of mineralocorticoids and glucocorticoids.
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14
Q

How is congenital adrenal hyperplasia treated?

A

By replacing lost glucocorticoids and mineralocorticoids.

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15
Q

List 3 symptoms of glucocorticoid excess.

A

1 - Obesity.

2 - Osteoporosis.

3 - Suppression of LH and FSH due to increased negative feedback, causing amenorrhoea.

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16
Q

List 2 symptoms of glucocorticoid insufficiency.

What causes these symptoms?

A

1 - Anovulation.

2 - Oligomenorrhea.

  • This is due to exaggerated production of LH and FSH due to decreased negative feedback.
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17
Q

Define oligomenorrhoea.

A

Infrequent menstruation.

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18
Q

Define chronic anovulation.

A
  • Infrequent bleeding intervals of >35d.

or

  • Frequent bleeding intervals of <21d.
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19
Q

List 5 clinical signs of androgen excess.

A

1 - Hirsutism.

2 - Acne.

3 - Androgenic alopecia.

4 - Virilisation in women.

5 - Hypertension.

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20
Q

Which molecule, when in excess, is used as an indicator of androgen excess?

A

Testosterone.

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21
Q

What is polycystic ovarian syndrome (PCOS) according to the Rotterdam consensus criteria for diagnosis?

A
  • A syndrome characterised by 2 out of the following 3 criteria:

1 - The presence of 26 or more ovarian follicles of 2-9mm in diameter and / or an increased ovarian volume.

2 - Androgen excess.

3 - Oligo- and/or anovulation.

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22
Q

What is the incidence of PCOS in women?

How does this compare to congenital adrenal hyperplasia in all births?

A
  • PCOS has an incidence of 10% in women.

- Congenital adrenal hyperplasia has an incidence of 1/15,000 of all births.

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23
Q

List 5 conditions that people with PCOS are at higher risk of developing.

A

1 - Insulin resistance.

2 - Hypertension.

3 - Type 2 diabetes.

4 - Liver disease.

5 - Cardiovascular disease.

24
Q

List 3 causes of androgen excess other than PCOS and congenital adrenal hyperplasia.

A

1 - Tumours.

2 - Cushing’s disease.

3 - Ovarian hyperthecosis.

25
Q

What is ovarian hyperthecosis?

A

A benign hyperplasia of the theca cells of the ovaries.

26
Q

Define adrenal incidentaloma.

A

An adrenal mass that has been incidentally discovered by imaging.

27
Q

What is the incidence of adrenal tumours?

A

3-5% in the general population.

28
Q

List 2 investigations that must be done when an adrenal incidentaloma is discovered.

A

1 - Whether the adrenal incidentaloma is related to excess adrenal hormone production.

2 - Whether the adrenal incidentaloma is malignant.

29
Q

Give an example of a problem with adrenal imaging.

A

Adrenal imaging is sensitive but not very specific, so multiple imaging modalities are often needed, which is costly and causes worry.

30
Q

What is the procedure for attributing a known adrenal tumour as the cause of excess adrenal hormone production?

A

1 - Exclude primary aldosteronism.

2 - Exclude Cushing’s.

3 - Exclude adrenal androgen excess (PCOS or CAH).

4 - Exclude phaeochromocytoma.

31
Q

How is primary aldosteronism diagnosed?

A

By pairing plasma renin and plasma aldosterone.

32
Q

How is Cushing’s syndrome diagnosed?

A

1 - Dexamethasone, a synthetic long-lasting glucocorticoid, is administered overnight.

2 - It occupies the glucocorticoid receptors in the hypothalamus and pituitary for much longer than the normal physiological glucocorticoids.

3 - The next morning, a blood sample is taken and endogenous glucocorticoid production is measured.

4 - Patients with Cushing’s syndrome will not have suppressed glucocorticoid production.

33
Q

What is a phaeochromocytoma?

A

A tumour arising from the chromaffin tissue of the adrenal medulla that causes excess production of catecholamines.

34
Q

List the 3 catecholamines.

A

1 - Adrenaline.

2 - Noradrenaline.

3 - Dopamine.

35
Q

List the breakdown products of adrenaline and noradrenaline.

When are adrenaline and noradrenaline normally broken down?

A

1 - Metanephrine.

2 - Normetanephrine.

  • Adrenaline and noradrenaline are constantly being broken down as part of normal biological processes.
36
Q

Which substance is measured when diagnosing a phaeochromocytoma?

Why?

A
  • Metanephrines.

- Metanephrines stay in the blood for longer than normetanephrines so are more suitable as a diagnostic test.

37
Q

List 2 characteristics of adenomas that are used to differentiate them from carcinomas in imaging.

A

1 - Adenomas are more homogenous than carcinomas.

2 - Adenomas have a higher fat content than carcinomas due to the presence of cholesterol.

38
Q

How is fat content measured in CT scans?

A

By measuring the tissue density (units of Hounsfields).

39
Q

What tissue density of an adrenal tumour is indicative of an adenoma (as opposed to a carcinoma)?

Why?

A
  • 10 Hounsfields or less.

- Such a low density is indicative of a high fat content, which is characteristic of adrenal adenomas.

40
Q

List 3 treatments for adrenal tumours:

A

1 - Surgical removal of the tumour.

If the tumour is not amenable to surgery:

2 - Mitotane with chemotherapy.

41
Q

What is mitotane?

A

An adrenal cytotoxic agent (the mechanism is unknown).

42
Q

When is an adrenal biopsy recommended?

A

When there is a history of extra-adrenal malignancy and all of the following additional criteria are fulfilled:

1 - The lesion is hormonally inactive (phaeochromocytoma has been excluded).

2 - The lesion has not been conclusively characterised as benign by imaging.

3 - Management would be altered by the knowledge of this histology.

43
Q

What is the name of tumours of sympathetic ganglia outside of the adrenal medulla?

A

Paragangliomas.

44
Q

What is multiple endocrine neoplasia (MEN)?

A

A combination of:

1 - Phaeochromocytoma.

2 - Medullary thyroid carcinoma.

3 - Parathyroid hyperplasia (characteristic of MEN2A).

4 - Mucocutaneous neuroma (MEN2B).

45
Q

What causes multiple endocrine neoplasia?

A

Mutation of the RET protooncogene.

46
Q

Define protooncogene.

A

A normal gene which, when mutated, becomes an oncogene.

47
Q

What is Von Hippel Lindau syndrome?

A

A combination of:

1 - Haemanigoblastoma.

2 - Phaeochromocytoma.

3 - Renal angioma.

4 - Renal cancer.

48
Q

List the organs that are affected by haemangioblastomas.

A

1 - Cerebellum.

2 - Retina.

3 - Spinal cord.

49
Q

What are angiomas?

A

Benign tumours derived from endothelial cells.

50
Q

What causes Von Hippel Lindau syndrome?

A

Mutations to the VHL gene.

51
Q

What is neurofibromatosis?

A

A group of genetic conditions which cause tumours to develop in nervous tissue.

52
Q

List 2 characteristics of neurofibromatosis.

A

1 - Neurofibromas.

2 - Café au lait patches.

53
Q

What is succinyl dehydrogenase?

What is significant about mutations to the B subunit of succinyl dehydrogenase?

A
  • An enzyme involved in the Krebs cycle.

- Mutations to the B subunit of succinyl dehydrogenase usually result in malignant phaeochromocytomas.

54
Q

List 4 common complications of phaeochromocytomas.

A

1 - Hypertension.

2 - Postural hypotension (due to low plasma volume).

3 - Tachycardia.

4 - Myocardial infarction.

55
Q

List 4 treatments of phaeochromocytomas.

A

Alpha blockade:

1 - Phenoxybenzamine.

2 - Doxazosin.

Beta blockade:

3 - Propranolol.

Other:

4 - Surgery, but only if alpha blockers have been given first.

5 - Chemotherapy.

56
Q

Why is alpha blockade necessary before surgery to remove a phaeochromocytoma?

A

If pressure is applied to a phaeochromocytoma without prior alpha blockade, a large amount of catecholamines are released.