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Gastrointestinal Block > Hyperaldosteronism, CAH, Phaeochromocytoma > Flashcards

Hyperaldosteronism, CAH, Phaeochromocytoma Flashcards

1
Q

a) where are juxtaglomerular cells found and what do these do?
b) where is angiotensinogen secreted from?
c) where is AT I converted into AT II?

A

a) afferent arteriole, sense low BP
b) the liver
c) the lungs

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2
Q

What type of hormone is aldosterone?

From where is it secreted

A

mineralocorticoid - secreted from the zona glomerulosa of the adrenal gland

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3
Q

List 3 actions of aldosterone

A
  1. ↑ Na+ reabsorption from DCT
  2. ↑ K+ secretion from DCT
  3. ↑ H+ secretion from CD
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4
Q

What is Primary Hyperaldosteronism?

A

When the adrenal glands are directly responsible for producing too much aldosterone

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5
Q

How does hyperaldosteronism present?

A
  1. Hypertension
  2. Hypokalaemia → muscle weakness
  3. Alkalosis
  4. Polyuria and polydipsia
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6
Q

List the two most common causes of Primary hyperaldosteronism

A
  1. Bilateral adrenal hyperplasia
  2. Adrenal adenoma → Conn’s syndrome
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7
Q

What classic triad should make you suspect possible Conns syndrome?

A
  1. Hypertension
  2. Hypokalaemia
  3. Alkalosis
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8
Q

What is Secondary Hyperaldosteronism?

A

Where excessive renin stimulating the adrenal glands to produce more aldosterone

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9
Q

List 3 causes of secondary hyperaldosteronism

Highlight the most common

A
  1. Renal artery stenosis
  2. Renal artery obstruction
  3. Heart failure
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10
Q

Compare levels of renin in primary vs secondary hyperaldosteronism

A

1o Serum renin is low as it is suppressed by the high BP

2o Serum renin is high

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11
Q

What is Renal artery stenosis

In which patients is it more commonly found and how it it diagnosed?

How does it lead to hyperaldosteronism?

A

Narrowing of the artery supplying the kidney

Usually found in patients with atherosclerosis, can be confirmed with a doppler ultrasound, CT angiogram or MRA

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12
Q

What is the first-line investigation in suspected primary hyperaldosteronism?

What would results indicate

A

Plasma aldosterone / renin ratio

  • ↑ aldosterone, ↓ renin = primary hyperaldosteronism
  • ↑ aldosterone, ↑ renin = secondary hyperaldosteronism
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13
Q

If high aldosterone is found on first line investigation what is the next step?

A

Investigate for the cause:

  • CT / MRI to look for an adrenal tumour
  • Renal doppler ultrasound, CT angiogram or MRA for renal artery stenosis or obstruction
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14
Q

What is the gold standard for localising the cause of primary hyperaldosteronism?

A

Selective adrenal venous sampling

To distinguish between unilateral adenoma and bilateral hyperplasia

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15
Q

List 3 other investigations which may aid diagnosis of hyperaldosteronism

A
  1. Blood pressure (hypertension)
  2. Serum electrolytes (hypokalaemia)
  3. Blood gas analysis (alkalosis)
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16
Q

Management of Hyperaldosteronism

A

Bilateral adrenocortical hyperplasia → aldosterone antagonists ie. Spironolactone (nonselective), Eplerenone (selective)

Adrenal adenoma → surgical adrenalectomy

Renal artery stenosis → Percutaneous renal artery angioplasty via femoral artery

17
Q

☆ Hyperaldosteronism is the most common cause of what?

A

Secondary Hypertension

If you have a patient with ↑BP that is not responding to treatment consider screening for hyperaldosteronism with a renin:aldosterone ratio

18
Q

What is Congenital adrenal hyperplasia?

A

Autosomal recessive condition caused by a congenital deficiency in enzymes required for adrenal steroid biosynthesis

Causes underproduction of cortisol and aldosterone and overproduction of androgens from birth

19
Q

Which enzymes may be affected in CAH?

Highlight the most common

A

21-hydroxylase deficiency (90%)

11-beta hydroxylase deficiency (5%)

17-hydroxylase deficiency (very rare)

20
Q

Pathophysiology of Congenital Adrenal Hyperplasia?

A

21-hydroxylase converts progesterone to aldosterone and cortisol

Progesterone is also used to create testosterone, but this doesn’t rely on 21-hydroxylase

In CAH, the defect in the enzyme means there is extra progesterone that is not converted to aldosterone or cortisol, and instead is converted to testosterone

21
Q

When and how does CAH present in non-classic (mild) form?

Incl both male and female

A

During childhood or after puberty. Sx related to ↑ androgens

Females:

  • Tall for their age
  • Deep voice
  • Early puberty
  • Facial hair
  • Absent periods

Male patients:

  • Tall for their age
  • Deep voice
  • Early puberty
  • Large penis
  • Small testicles
22
Q

When and how does CAH present in classic (severe) form?

A

Females present at birth with: virilised genitalia “ambiguous genitalia” and an enlarged clitoris

Males present with little signs at birth except, salt-losing form presents at 7-14 days with:

  • hyponatraemia, hyperkalaemia (arrhythmias), hypoglycaemia
  • poor feeding, vomiting and dehydration
23
Q

What other feature on appearance tends to occur in CAH

A

Skin hyperpigmentation

Anterior pituitary responds to ↓cortisol by ↑ACTH. Byproduct of ACTH is melanocyte simulating hormone which (+) melanin within skin cells

24
Q

Management of CAH

A

Hydrocortisone → cortisol replacement

Fludrocortisone → aldosterone replacement

Female patients with “virilised” genitals may require corrective surgery

25
Q

Which organ and specific cell type produce adrenaline

A

Adrenaline produced by the “chromaffin cells” in the adrenal medulla of the adrenal glands

26
Q

What is a Phaeochromocytoma?

A

Tumour of the chromaffin cells that secretes unregulated and excessive amounts of adrenaline

27
Q

What is adrenaline and what is its function

A

Adrenaline is a “catecholamine” hormone and NT that stimulates the SNS and is responsible for the “fight or flight” response

28
Q

What gene may be assocuated with Phaeochromocytoma?

A

25% are familial - a/w multiple endocrine neoplasia type 2 (MEN 2)

29
Q

What is the 10% rule ofP haeochromocytomas?

A
  1. 10% bilateral
  2. 10% cancerous
  3. 10% outside the adrenal gland
30
Q

How is Phaeochromocytoma diagnosed?

A
  1. 24 hour urine catecholamines
  2. Plasma free metanephrines
31
Q

Why do we not measure adrenaline for diagnosis of Phaeochromocytoma

A

Adrenaline has a short half life of only a few minutes in the blood

Metanephrines (breakdown product of adrenaline) have a longer half life

Hense metanephrines are less prone to dramatic fluctuations and a more reliable diagnostic tool

32
Q

How does Phaeochromocytoma present?

A

Signs and symptoms fluctuate relating to periods when tumour is secreting adrenaline

  1. Anxiety
  2. Sweating
  3. Headache
  4. Hypertension
  5. Palpitations, tachycardia and paroxysmal atrial fibrillation
33
Q

Management of Phaeochromocytoma?

A
  1. Alpha blockers (i.e. phenoxybenzamine)
  2. Beta blockers once established on alpha blockers
  3. Adrenalectomy to remove tumour is the definitive management

Gastrointestinal Block (26 decks)

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