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Endocrine System > Adrenal > Flashcards

Adrenal Flashcards

1
Q

What is the precursor of all steroid hormones?

A

Cholesterol

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2
Q

What 2 things facilitate the formation of pregnenolone and progesterone (precursors for cortisol and sex steroids) from cholesterol?

A

1) Angiotensin II
2) ACTH

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3
Q

How is cortisol production limited to the zona fasciculata and reticularis?

A

17-hydroxylase (enzyme for cortisol synthesis) is only located in the zona fasciculata and reticularis (not in glomerulosa)

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4
Q

How is aldosterone secretion regulated?

A

1a) ↓BP detected by Macula Densa → paracrine signalling to JG cells → renin

b) Renin convert Angiotensinogen (liver) to AT1

c) ACE convert AT1 to AT2 in lungs

d) AT2 lead to production of aldosterone in adrenal medulla

2) High K+

3) ACTH

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5
Q

What are the 2 renal actions of aldosterone?

A

1) ↑ Na retention in collecting ducts → ↑ECF voliume

2) ↑K+ secretion → ↓K+ conc.

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6
Q

Would hypovolemia cause K+ loss physiologically?

A

No
- hypovolemia along actives RAAS but AT2 inhibits K+ channels

whereas in hyperK+
- renin is inhibited → ↓inhibition of K+ channels
- but activation of aldosterone by high K+

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7
Q

How does one assess if there is an issue with aldosterone production?

A

Measure aldosterone:renin ratio

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8
Q

What are 4 biological effects of cortisol?

A

1) Survival during stress
2) Vascular reactivity to catecholamine
3) Intermediary metabolism
4) Immune suppression
5) Anti-inflammatory effect

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9
Q

How is cortisol secretion regulated?

A

Hypothalamus → CRH
Pituitary → ACTH
Adrenal cortex → Cortisol

1) -ve feedback of cortisol on pituitary and hypothalamus

2) Stress and diurnal rhythm (high in morning, low at night)

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10
Q

What are 2 causes of adrenal failure/Addison’s disease?

A

1) Adrenal gland failure (1°)
2) ACTH deficiency (2°)

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11
Q

What are 2 symptoms and signs of Addison’s disease?

A

1) Fatigue
2) Increased skin pigmentation
3) Hypotension (90/55)
4) HyperK+ (5.6mM) (N: 3.5-5.2)

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12
Q

When is Dexamethasone used at high-dose to discern the source of excess cortisol?

A

To distinguish between a pituitary and ectopic source

  • pituitary will be suppressed @ high dose but ectopic (eg. lung tumour) will not
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13
Q

What is used to assess the source of excess cortisol (Cushing’s syndrome)?

A

Dexamethasone

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14
Q

If ACTH is low but cortisol is in excess, what is the likely source of excess cortisol?

A

Adrenal

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15
Q

If ACTH is normal/high but cortisol is in excess, what is the likely source of excess cortisol?

A

Pituitary or ectopic
- distinguish with high dose dexamethasone

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16
Q

How is the source of cortisol deficiency tested for?

A

Administer synthetic ACTH

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17
Q

In a primary adrenal gland dysfunction, which hormones would be deficient?

A

1) Cortisol
2) Aldosterone

18
Q

How are primary and secondary cortisol deficiencies differentiated?

A

Administration of synthetic ACTH
- if cortisol restored → 2° issue (can produce, no stimulus/pituitary or hypothalamus issue)
- if cortisol still low → 1° issue (adrenal dysfunction)

19
Q

What are the differences between primary and secondary adrenal insufficiency?

A

1) Affected organ
- 1°: adrenal glands affected
- 2°: pituitary/hypothalamus affected

2) Skin
- 1°: dark
- 2°: pale

3) ACTH
- 1°: high
- 2°: not high

4) Aldosterone
- 1°: deficient
- 2°: usually ok

20
Q

What are 2 conditions of adrenocortical hormone excess?

A

1) Cushing’s Syndrome:
- DM, 2° HT, Osteoporosis, HypoK+

2) Aldosteronism:
- HT, HypoK+, Metabolic Acidosis

21
Q

What are 2 conditions of adrenocortical hormone deficiency?

A

1) Addison’s disease (1°)
2) Congenital adrenal hyperplasia (1°)
3) ACTH deficiency (2°)

22
Q

What is the name for a tumour in the adrenal medulla and what are the associated symptoms?

A

Pheochromocytoma
- episodic headache
- sweating
- tachycardia

23
Q

What is Cushing syndrome?

A

Hyperadrenocorticism

24
Q

What are 4 causes of Cushing’s syndrome?

A

1) Iatrogenic (eg. exogenous glucocorticoids)
2) Cushing’s disease (pituitary ACTH secreting adenoma)
3) Adrenal cortical tumour (adenoma, carcinoma)
4) Ectopic ACTH production (eg. SCC of lung)

25
Q

What are 5 clinical features of Cushing’s syndrome?

A

1) Central obesity
2) HTN
3) Glucose intolerance
4) Plethoric faces
5) Purple striae
6) Hirsutism
7) Menstrual dysfunction
8) Muscle weakness
9) Bruising
10) Osteoporosis

26
Q

How is Cushing’s Syndrome diagnosed?

A

1) Urinary-free cortisol
2) Overnight Dexamethasone Test (1mg @ midnight, serum cortisol <140nMol/L at 8am)
- failure to suppress → Cushing’s
3) Low dose DTS using 0.5mg, 6-hourly for 48 hours (negative if cortisol <50nmol/L)

27
Q

What is Conn’s syndrome?

A

Primary hyperaldosteronism

28
Q

What are 2 causes of primary hyperaldosteronism/COnn’s syndrome?

A

1) Adrenal aldosterone producing adenoma (APA)
2) Idiopathic hyperaldosteronism w bilateral adrenal hyperplasia (BAH)

29
Q

What are 3 signs of primary hyperaldosteronism?

A

Loss of -ve feedback with ↑↑Aldosterone
1) Metabolic alkalosis
2) HypoK+
3) Hypertension
4) ↑Blood volume
5) ↓Renin

30
Q

What are 3 biochemical tests for primary hyperaldosteronism?

A

1) HypoK+ w inappropriate kaliuresis
2) Plasma aldosterone conc. (PAC)
3) Plasma renin activity (PRA)

31
Q

What is a Phaechromocytoma?

A

Adrenal Medullary Tumour
- 30-50 y/o
- MEN type IIa and IIb

10%:
- bilateral/multiple
- malignant
- extra adrenal
- familial
- recurrent

32
Q

What are 4 signs and symptoms of pheochromocytoma?

A

1) Hypertension (can be intermittent, sustained or paroxysms superimposed)
2) Headache
3) Sweating
4) Palpitations & Tachycardia

33
Q

What are 8 tests for catecholamine-secreting tumours (eg. Pheochromocytoma)?

A

Serum:
1) Free catecholamines (EPI, NE, DA)
2) Metanephrines
3) Chromogranins A, B, C
4) Pancreastatin
5) Neuropeptide Y

Urine:
1) Free catecholamines (EPI, NE, DA)
2) Metanephrines
3) VMA or HMMA
4) ISO-VMA
5) HVA
6) DHPG

34
Q

What are 5 causes of primary chronic adrenal insufficiency?

A

1) Idiopathic adrenal atrophy (autoimmune adrenalitis)

2) Granulomatous diseases (TB, Histoplasmosis, Sarcoidosis)

3) Neoplastic infiltration

4) Haemochromatosis

5) Amyloidosis

6) Post bilateral adrenalectomy

35
Q

What are 4 causes of secondary chronic adrenal insufficiency?

A

1) Tumours
- pituitary tumour
- craniopharyngioma
- tumour of third ventricle

2) Pituitary infarction/haemorrhage
- postpartum necrosis (Sheehan syndrome)
- haemorrage in tumours

3) Granulomatous diseases
- Sarcoidosis

4) Post-hypophysectomy

5) Prolonged-exogenous steroid administration

36
Q

What are 8 clinical features of primary adrenal insufficiency?

A

Glucocorticoid deficiency
1) Weakness
2) Hypogly
3) WL
4) GI discomfort

Mineralocorticoid deficiency
1) Na wasting
2) Hypovolemia
3) Postural hypotension
4) HyperK+
5) Pigmentation
6) Patches of vitiligo (sometimes for autoimmune adrenalitis)

37
Q

What is Addison’s disease?

A

Adrenal insufficiency

38
Q

What are 5 clinical features of secondary adrenal insufficiency?

A

Glucocorticoid deficiency
1) Weakness
2) Hypogly
3) WL
4) GI discomfort

**No symptoms of Mineralocorticoid deficiency
BUT: May have other pituitary hormone deficiency:
1) Hypogonadism
2) Hypothyroidism

39
Q

How is Addison’s disease diagnosed?

A

Short synacthen test
- basal and post ACTH (IV 250ug @ 30 and 60mins)
- cortisol should ↑ to >550nmol/L or 2-2.5 fold increase in basal values

40
Q

How is primary and secondary Addison’s disease differentiated?

A

Long Synacthen Test
- 1mg Depot-Synacthen given IM
- plasma cortisol measured before and 1, 2, 4, 6, 24, 48

Primary:
- no rise at all or minimal

hypopit/adrenal suppression: rise is delayed and attenuated

Normal:
immediate and sustained rise in plasma cortisol

Endocrine System (9 decks)

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