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Lec4 Adrenal causes of hypertension Flashcards

1
Q

What is the location of the adrenal glands?

A

Superior pole of the kidneys, retroperitoneal - around T12

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2
Q

How big are the adrenal glands?

A

1.5 inches in height x 3 inches in length

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3
Q

What do the adrenals looks like on a CT scan (cross section through it)?

A

Inverted Y shape

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4
Q

Name the layers of the adrenal glands

A

Zona glomerulosa
Zona Fasciculata
Zona Reticularis
Medulla

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5
Q

What do each of the layers produce?

A

G - produces Aldosterone - swaps sodium for potassium
F - produces Cortisol - elevates blood glucose
R- produces adrenal androgens - sex hormones

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6
Q

What are the three adrenal causes of hypertension?

A
  1. Primary Hyperaldosteronism
  2. Phaeochromocytoma
  3. Some forms of Congenital Adrenal Hyperplasia
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7
Q

Which layer in the adrenal gland contributes to primary hyperaldosteronism?

A

Zona Glomerulosa - because it produces aldosterone

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8
Q

What can cause the zone glomerulosa to produce excess aldosterone?

A

Adenoma of the ZG - a single, enlarged node producing excess aldosterone
Hyperplasia - enlarged tissue
Rare genetic causes

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9
Q

How does excess aldosterone produced in the zone glomerulosa cause hypertension?

A

Excess aldosterone causes excess sodium to be reabsorbed in the kidney tubule and so water also follows and is reabsorbed, which leads to HYPERTENSION

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10
Q

In which layer of the adrenal gland does a phaeochromocytoma develop?

A

Adrenal medulla

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11
Q

What is a phaeochromocytoma (phaeo)?

A

A tumour of the adrenal medulla which results in high levels of noradrenaline and adrenaline

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12
Q

What is Congenital Adrenal Hyperplasia?

A

It is an uncommon enzyme defect

leads to a build up of aldosterone, causing hypertension

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13
Q

What kind of molecule is aldosterone?

A

Mineralocorticosteroid

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14
Q

Describe the pathway for aldosterone secretion

A

When the kidneys are under perfused this is sensed by baroreceptors in the renal artery
The kidney responds by producing RENIN
Renin catalyses the reaction which turns ANGIOTENSINOGEN into ANGIOTENSIN I
ANGIOTENSIN CONVERTING ENZYME - ACE - catalyses conversion of ANGIOTENSIN I into ANGIOTENSIN II
Angiotensin II causes production of ALDOSTERONE which acts on the kidney and causes water to be reabsorbed
This INCREASES BLOOD PRESSURE

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15
Q

What is Conn’s Syndrome?

A

A condition in which there is excess aldosterone

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16
Q

Why is it important to distinguish between primary hyperaldosteronism (PA) /Conn’s syndrome and essential hypertension?

A

Because Conn’s syndrome is a potentially curable cause of high blood pressure

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17
Q

What type of patients would you screen for PA?

A
  1. Hypokalaemic patients - this might be due to high aldosterone
  2. Resistant hypertension patients - on 3 hypotensive drugs
  3. Young people - there is much more likely to be an underlying cause for their hypertension
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18
Q

Why are patients with PA worse off than patients who just have straight forward hypertension?

A

Because PA patients have more vascular and renal pathology than a patient with essential hypertension with the same blood pressure

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19
Q

What is the initial screening test for PA?

A

Suppressed renin with normal/high aldosterone indicates PA

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20
Q

What is the confirmatory test for PA?

A

Oral or IV Na+ suppression test
If there is a high sodium, you expect the aldosterone to be low because there is no need for more production of aldosterone when sodium is high
If there is normal to high aldosterone at high levels of sodium then there is inappropriate aldosterone production

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21
Q

What are the tests for specific aetiology of PA? i.e. secreting adenoma or bilateral hyperplasia

A
  1. Adrenal CT scan
  2. Adrenal venous sampling - to see if the aldo secretion is uni/bilateral
  3. Metomidate PET CT
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22
Q

Older adults often have nodules in their adrenal glands which are harmless. True or False?

A

True

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23
Q

What forms of treatment are there for Unilateral adenoma in Primary Hyperaldosteronism?

A 
Laparascopic adrenalectomy 
Medical treatment (sometimes)
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24
Q

What is the treatment for Bilateral Hyperplasia in PA?

A

Medical treatment with ALDOSTERONE ANTAGONISTS

e.g. Spironolactone and Eplerinone

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25
Q

What is the function of both spironolactone and eplerinone?

A

To bring blood pressure down

26
Q

What is a potential side effect of spironolactone?

A

It causes poor oestrogen regulation which can cause megalogynaecomastia in men

27
Q

What is a phaeochromocytoma?

A

A tumour of the adrenal medulla

28
Q

What type of cells make up the adrenal medulla?

A

Modified post-ganglionic nerve cells

29
Q

What are the modified post-ganglionic nerve cells of the adrenal medulla innervated by?

A

Preganglionic nerves

30
Q

Cholinergic nerves from the Spinal Cord stimulate the adrenal medulla which results in:

A

production of tyrosine, conversion to L-DOPA, which is converted to dopamine and dopamine is converted to noradrenaline.

31
Q

What is the function of the adrenal medulla?

A

The adrenal medulla secretes dopamine, noradrenaline and adrenaline into the circulation

32
Q

What triggers the conversion of noradrenaline to adrenaline in the adrenal medulla?

A

Cortisol release from the cortex

33
Q

What is adrenomedullin?

A

A peptide associated with phaeochromocytoma.

It is thought to be one of the most potent endogenous vasodilatory peptides in the body

34
Q

What type of tissue is the adrenal medulla?

A

Neuroendocrine tissue

35
Q

Is the adrenal medulla essential for life?

A

No - but it would be very difficult without it

36
Q

What response is the adrenal medulla responsible for?

A

Stress response and

Fight or flight response

37
Q

What are the biological effects of noradrenaline?

A

Vasoconstriction - increased BP, pallor

Glycogenolysis - to provide more glucose/substrate for the muscles for “fight or flight”

38
Q

What receptors does noradrenaline act on?

A

Alpha 1 and alpha 2 receptors (so NA is a alpha 1 and 2 agonist)

39
Q

What receptors does adrenaline act on?

A

Alpha 1, beta 1 and beta 2 receptors (so adrenaline is a alpha 1, beta 1 and 2 agonist)

40
Q

What are the biological effects of adrenaline?

A

Vasoconstriction
Vasodilation in muscle
Increased HR
Sweating

41
Q

What is the main pathology of the adrenal medulla?

A

Phaeochromocytoma

42
Q

Where are 20% of phaeos diagnosed?

A

In the mortuary

43
Q

Describe the presentation of Phaeos

A

Spells of headache, sweating, pallor, palpitation, anxiety
Hypertension:
Permanent
Intermittent - but may not pick this up, depends on when BP taken

44
Q

Name the autosomal dominant genetic conditions associated with phaeochromocytoma

A

Neurofibromatosis Type 1 (NF1)
Multiple Endocrine Neoplasia Type 2 (MEN2)
Von Hippel-Lindau Syndrome

45
Q

Describe the presentation of NF1

A

Tumours under the skin or deeper = neurofibromas

Axillary freckling also occurs in NF1

46
Q

What are neurofibromas?

A

Neurofibromas - tumours along the nerves which are made up of cells that surround nerves and other cell types

47
Q

How many neurofibromas can a person with NF1 have?

A

Any number from none to hundreds

48
Q

At what age do neurofibromas present?

A

At any age but especially during adolescence

49
Q

What is a type of cancer found in MEN2 family members?

A

Medullary carcinoma of the thyroid

Metastasis of this type of cancer can kill

50
Q

What can be done if a child is known to have MEN2?

A

Take out the thyroid gland to prevent death from metastasis of Medullary Carcinoma of the Thyroid

51
Q

Name a complication of Von Hippel Lindau Syndrome

A

Retinal haemoblastoma - tumour in the retina

Cerebellar haemangioligoblastoma

52
Q

What tests do you do to diagnose a phaeo?

A

24 hour urine

Plasma/blood test

53
Q

What do you measure in the 24 hour urine test?

A

Normetanephrines and metanephrines - metabolites of catecholamines which would be high in a phaeo pt
3 methyoxytromine

54
Q

What do you measure in the blood test?

A

Plasma levels of catecholamines (adrenaline, noradrenaline) and metanephrines

55
Q

What complicates measuring catecholamines?

A

There are other conditions that elevate catecholamines

56
Q

What other conditions cause elevated catecholamines?

A

Obstructive Sleep Apnoea
Amphetamine like drugs
L-DOPA
Labetalol

57
Q

Where does the dopamine in urine come from?

A

The kidney and nervous system - NOT the adrenal medulla

58
Q

What can you measure instead that will give an idea about the adrenal medullary activity?

A

3 methoxytyramine in the urine

59
Q

What imaging can be done to find a phaeo?

A

CT scan

Meta-iodobenzylguanidine Scintiscan

60
Q

What is a MIBG scan?

A

A type of scanning using a radioisotope (iodine) “tracer” to determine the presence of phaeochromocytomas and neuroblastomas

61
Q

How do you manage a phaeo?

A 
Alpha antagonists (phenoxybenzamine and doxazocin)
Beta antagonists (propanolol)
Laparoscopic adrenalectomy
62
Q

What type of post adrenalectomy care would you consider?

A

Consider genetic testing - 30% are genetic and 13 mutations are identified so far
Check metanephrines annually with 24 hour urine/ plasma
Additional treatment if malignant - the case for 10%

Endocrinology (11 decks)

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