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Endocrinology > Adrenal Glands > Flashcards

Adrenal Glands Flashcards

1
Q

Where are the adrenal glands found?

A

On top of the kidneys

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2
Q

What do the adrenal glands produce?

A

Glucocorticoids - cortisol (carb, lipid and protein metabolism)

Mineralocorticoids (sodium and potassium balance)

Androgens (sex hormones - converted into testosterone peripherally)

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3
Q

What controls androgen and corticosteroid release?

A

Corticotropin-releasing factor from hypothalamus

Stimulates ACTH production from pituitary

This acts on adrenal cortex

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4
Q

What is Cushing’s syndrome?

A

Clinical state from excess glucocorticoids

Loss of normal feedback mechanisms from hypothalamo-pituitary-adrenal axis

Loss of circadian rhythm of cortisol secretion

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5
Q

What is main cause of Cushing’s syndrome?

A

Oral steroids

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6
Q

How do you initially confirm the diagnosis of Cushing’s syndrome?

A

Raised plasma cortisol

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7
Q

Tests for investigating Cushing’s syndrome?

A

Overnight dexamethasone suppression test - give 1mg at night and 8am cortisol should be suppressed - no suppression in cushing’s syndrome

48hour dexamethasone suppression test - give 0.5mg every 6 hours for 2 days - measure cortisol at 0 and 48 hours - won’t be suppressed in cushing’s syndrome

48 hour high dose - give 2mg

Midnight cortisol measurement - when it is lowest normally - in cushing’s it is still high

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8
Q

Localisation tests in Cushing’s syndrome

A

If ACTH is undetectable - likely to be an adrenal tumour

If ACTH is high - could be pituitary cause or ectopic ACTH production

To distinguish - high dose test will have suppression with pituitary cause but not if from other cause

CRH test - if pituitary cause then cortisol will rise - if it is ectopic ACTH production then CRH will have no effect

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9
Q

Commonest cause of increased ACTH

A

Pituitary adenoma = Cushing’s disease

Usually a microadenoma and it causes bilateral adrenal hyperplasia

Peak age 30-50 years

Very high dose suppression test can decrease cortisol slightly

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10
Q

Two other causes of raised ACTH levels

A

1) Ectopic ACTH production - especially small cell lung carcinoma and carcinoid tumours - weight loss, hyperglycaemia and classic cushings features often absent
- even high dose suppression test won’t have an effect

2) Ectopic CRH production
- rare, some thyroid and prostate cancers

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11
Q

Signs of high plasma ACTH

A

Will get pigmentation (due to ACTH cross reacting with melanin receptors)

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12
Q

What can you get with very high cortisol levels

A

Increased mineralocorticoid activity therefore hypokalaemic metabolic alkalosis

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13
Q

4 ACTH-independant causes of Cushing’s syndrome

A

Adrenal adenoma (can get virilization)

Adrenal nodular hyperplasia

Iatrogenic - STEROIDS

Rarely - Carney Complex causing endocrine tumours

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14
Q

Symptoms of Cushing’s Syndrome

A 
Weight gain
Fatigue
Mood change (depression, lethargy)
Acne
Proximal weakness 
Gonadal dysfunction - irregular menses, hirsutism, ED
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15
Q

Signs of Cushing’s syndrome

A

Moon face, plethoric face

Buffalo neck hump, supraclavicular pattern and central obesity

Bruises, poor healing and purple abdominal striae

Skin (thin) and muscle atrophy

Osteoporosis

High BP and glucose

Pigmentation if ACTH dependant

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16
Q

Treatment of Cushing’s disease

A

Removal pit adenoma

Can always do removal of adrenals if source un-locatable or recurrence post-op - can be Nelsons syndrome where pit enlarges following loss of negative feedback from adrenals - increased ACTH production

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17
Q

Metyrapone

A

Suppresses cortisol secretion - can be used pre-op

Cortisol also suppressed by ketoconazole

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18
Q

Prognosis of Cushing’s

A

Good if treated, vascular complications if not treated. Effects of Cushing’s often remain eg. obesity, menstrual irregularity

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19
Q

What is Addison’s Disease?

A

Primary adrenocortical insufficiency - not enough corticosteroids produced by adrenal cortex

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20
Q

Prevalence of Addison’s Disease?

A

0.8/100,000 but can be fatal

21
Q

Main cause of AD in UK?

A

80% are due to autoimmunity

22
Q

Other causes of AD

A

TB, opportunistic infection from HIV, adrenal mets, lymphoma, adrenal haemorrhage, or congenital (late-onset adrenal hyperplasia)

23
Q

Symptoms of AD

A

Lean, tanned, tearful, tired

Weakness, anorexia, dizziness, faints

Low mood

GI disturbances - nausea + vomiting and abdo pain

Postural hypotension (decreased mineralocorticoid production)

Pigmented palmar creases and buccal mucosa - high ACTH

24
Q

Electrolytes in Addisons disease

A

Low Na+ and high K+ (mineralocorticoid)

Ca2+ high

25
Q

Diagnosis of AD

A

In Addison’s 9am ACTH is high
9am cortisol levels if >550nmol/L then Addison’s is excluded

If below 100nmol/L then diagnostic of adrenal insufficiency

If between 100 and 550 then do short ACTH stimulation test
Synacthen test - tetracosactide given IM- ACTH analogue

Short ACTH is main diagnostic test for addisons

Adrenal autoantibodies in 80% (against 21-hydroxylase)

26
Q

Treatment of AD

A

Replace steroids (TDS) and mineralocorticoids
Hydrocortisone
Fludrocortisone to correct Na and K imbalances

27
Q

Prognosis in AD

A

Death caused by adrenal crises and infection

Mean age at death for men is 65 years therefore 11 years off life expectancy

Women only lose 3 years

28
Q

What is main cause of secondary adrenal insufficiency

A

Iatrogenic - long-term steroid therapy suppresses pit-adrenal axis

Only becomes apparent on withdrawal of steroids

29
Q

What does hyperaldosteronism cause?

A

Increased water and sodium retention (causing hypertension) along with increased K+ and H+ secretion in urine

Therefore suspect in anyone with hypertension, hypokalaemia and alkalosis - not on diuretics

30
Q

What signs can you get in hyperaldosteronism?

A

Signs of hypokalaemia (fast irregular pulse, chest pain and palpitations) polyuria, polydipsia, muscle weakness, paraesthesia, tetany and hypertension

31
Q

Causes of hyperaldosteronism

A

2/3 are solitary aldosterone producing adenoma = Conn’s syndrome

1/3 are bilateral adrenal hyperplasia

Rarer:
Adrenal carcinoma
Glucocorticoid-remediable aldosteronism (GRA) or glucocorticoid suppressible hyperaldosteronsim (GSH) - ACTH part of 11b hydroxylase gene fuses to aldosterone synthase gene and brings it under ACTH control - increasing aldosterone production - treat with dexamethasone

32
Q

K+ in hyperaldosteronism

A

Normally low but don’t rely on it as >20% are normokalaemic

Will be below 4mmol

33
Q

Treatment of Conn’s

A

Laparoscopic adrenalectomy - spironolactone 4weeks pre op to control BP and K+

34
Q

How do you treat a bilateral adrenal hyperplasia which is causing hyperaldosteronism

A

Spironolactone, amiloride, eplerenone (selective aldosterone receptor antagonist - doesn’t cause gynacomastia)
Can take 4-6 weeks for hypertension to respond to treatment

35
Q

Causes of secondary hyperaldosteronism

A

High renin from decreased renal perfusion

eg. renal artery stenosis, accelerated hypertension, diuretics, CCF or heart failure

36
Q

What is Bartter’s syndrome?

A

Major cause of congenital salt wasting - caused by a sodium and chloride leak in loop of henle via a defective channel

Sodium loss leads to volume depletion therefore increased renin and aldosterone production

Therefore hypokalaemia and metabolic alkalosis but not hypertension

37
Q

When does Bartter’s syndrome present and what with?

A

In childhood, failure to thrive, polyuria and polydipsia

38
Q

Treatment of Bartter’s syndrome

A

K+ replacement, NSAIDs and ACE-i

39
Q

What is phaeochromocytoma?

A

Catecholamine-producing tumour of chromaffin cells in adrenal medulla

Catecholamines usually involved in fight-or-flight response

40
Q

Genetic cause of phaeochromocytoma

A

90% are sporadic

10% are part of hereditary cancer syndrome

41
Q

How does phaeochromocytoma present?

A

Episodic headache, sweating and tachycardia/hypertension

Symptoms of tachycardia (palpitations, faints, angina, dyspnoea)

CNS symptoms

Psychological symptoms

GIT problems (D&V, abdominal pain and mass)

Also get fever and pallor and flushes

42
Q

What can precipitate symptoms of phaeochromocytoma?

A

Straining, exercise, stress, abdominal pressure, surgery, drugs

43
Q

Treatment of phaeochromocytoma?

A

Surgery, can do pre-op blockade with phenoyxbenzamin and beta-blockers too if needed

Lifelong monitoring needed as malignancy can recur late in life

44
Q

What is Congenital Adrenal hyperplasia?

A

Autosomal recessive defect in steroid synthesis pathway resulting in decreased cortisol and altered aldosterone production
Causes secondary rise in ACTH therefore adrenal gland hyperplasia and build-up of precursor steroids and androgenic steroids

45
Q

Most common defect in CAH

A

21-hydroxylase (also 11 beta and 17 alpha)

46
Q

Presentation of CAH

A

Salt-losing crisis in infants (hypotension, hyponatraemia and hyperkalaemia)
Ambiguous genitalia in females and precocious puberty in males

47
Q

What is increased in CAH with 21-hydroxylase deficiencu

A

17OH-progesterone

48
Q

Which ages are commonly affected by causes of hyperaldosteronism?

A

Adrenal adenoma is commonly women and younger

Older and men for BAH

49
Q

Diagnosis of hyperaldosteronism

A

Salt loading - failure of aldosterone suppression is diagnostic

Endocrinology (8 decks)

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