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Year 2(B3) - Endocrine > Week 4 - H - Adrenal disorders > Flashcards

Week 4 - H - Adrenal disorders Flashcards

1
Q

The adrenal glands are surrounding by a protective fatty capsule What is the outer and inner parts of the adrenal glands?

A

The adrenal glands have the outer adrenal cortex and inner adrenal medulla

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2
Q

What is the adrenal cortex separated into? (outer to inner)

A

Zona glomerulosa

Zona fasciculata

Zona reticularis

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3
Q

This is the histological appearance of the adrenal cortex regions What is each sections function?

A

Zona glomerulosa, Mineralocorticoids -Aldosterone

Zona fasciculata, Glucocorticoids - Cortisol

Zona reticularis, Sex steroids (androgen) and glucocorticoids

(Go Find Rex, Make Good Sex)

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4
Q

What is the rate limiting step in the synthesis of corticosteroids in the adrenal cortex?

A

The conversion of cholesterol to pregnenolone

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5
Q

What regulates the production of aldosterone from the adrenal cortex?

A

Aldosterone production regulated by renin-angiotensin system and plasma potassium

And regulated by potassium levels - increasing potassium causes an increase in aldosterone produdction

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6
Q

What causes the hypothalamus to secrete more CRH?

Which have a negative feedback effect on the hypothalamus/pituitary secretions:

Androgen produced by zona reticularis?

Cortisol produced by zona fasciculata?

Aldosterone produced by zona glomerulosa?

A

Stress, illness, time of day

Both Androgen produced by zona reticularis and Cortisol produced by zona fasciculata

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7
Q

How is a falling blood pressure corrected by the renin angiotensin system?

A

Blood pressure falls

Juxtaglomerular cells of kidney release renin

Renin converts angiotensinogen to angiotensin 1

Angiotensin 1 converted to angiotensin 2 by ACE

Angiotenins 2 stimulates adrenal cortex to secrete aldosterone

Aldosterone causes resorption of Na+ and H2O increasing blood volume –> increasing blood pressure

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8
Q

Just an image of the major cortisol effects

A

If ACTH cause of cushings, excess androgen as well as excess cortisol

Also redistribution of fat causes more androgen production

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9
Q

What are the 3 main principles of use of corticosteroids?

A

Suppress inflammation

Suppress immune system

Replacement treatment

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10
Q

What effect does an increased aldosterone have on potassium ions?

A

Increases potassium excretion

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11
Q

Primary adrenal insufficiency is when the problem is at the adrenal level What are 3 common causes of primary adrenal insufficiency?

A

Addison’s disease

Congenital Adrenal Hyperplasia (CAH)

Adrenal TB/malignancy

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12
Q

What do androgens go on to form in males and females?

A

In males becomes testosterone

In females becomes estrogen

Androgen insufficiecny can cause low sex drive and amenorrhea in females

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13
Q

What is the commonest cause of primary adrenal insufficiency? What percentage of the adrenal cortex is usually destroyed by the autoantibodies before symptoms arise? What is the usual antbody?

A

Addison’s disease

Autoimmune destruction of adrenal cortex >90% destroyed before symptomatic

Autoantibodies positive in 70% (21-alpha hydroxylase antibodies)

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14
Q

What are the clinical features of addisons disease?

A

Hyperpigmentation

Postural hypotension

Dizziness and low BP

Abdo pain, vomiting

Weight loss

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15
Q

What is the suspicious biochemistry when diagnosing a primary adrenal insufficiency?

A

Decreased sodium and increased potassium blood levels

Hypoglycaemia (due to the lack of cortisol)

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16
Q

What test is carried out for addisons disease? What is given?

A

Short synacthen test – stimulation test

– synthetic ACTH is given to see if the adrenal gland responds

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17
Q

What should be measured in a synacthen test?

A

Give synthetic ACTH (tetracosactide)

  • measure cortisol before and 1/2 hour after giving it - addisons excluded if coritsol >550nmol/l

* ACTH levels should be increased (causes skin pigmentation)

* Measure renin/aldosterone levels - increased renin but decreased aldosterone

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18
Q

What should be given as treatment in addison’s disease? (treatment for gluco and mineralo corticoids)

A

Hydrocortisone as cortisol replacement

  • Give IV if acutely unwell
  • Usually 15-30mg in daily divided doses to mimic diurnal rhythm

Fludrocortisone as aldosterone replacement– careful monitoring of BP and K

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19
Q

Patients who have Addison’s disease are usually given both glucocorticoid and mineralocorticoid replacement therapy. In patients’ with addison’s disease who present with an illness, how should the treatment be altered?

A

Double the glucocorticoid dose, keep the fludricortisone dose the same

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20
Q

What is the commonest cause of secondary adrenal insufficiency?

A

Exogenous steroid use

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21
Q

How does the exogenous steroid use cause an adrenal insufficiency?

A

Causes a negative feedback on the hypothalamus to not produce CRH and on the pituitary to not produce ACTH

The suppression of the hypothalamic pituitary adrenal axis leading to a decreased organic cortisol production only becomes apparent on withdrawal of the steroids

22
Q

What is the difference in features of secondary and primary adrenal insufficiency?

A

There is no tanned skin in secondary as ACTH is decreased

There is no hyperkalamia as aldosterone is regulated by RAAS

23
Q

Pituitary/hypothalamic disease

Tumours - Surgery/radiotherapy

This can also causes secondary adrenal insufficiency What is used to treat secondary adrenal insufficiency? is fludrocortisone required?

A

Give hydrocortisone for cortisol replacement

Fludrocortisone is not required to replace aldosterone as it is intact

24
Q

After a synacthen test, what should the 30 min plasma cortisol level increase to make primary or secondary adrenal insufficiency more likely?

A

Addison’s disease -

30min cortisol 550mmol/l

as adrenal glands still functioning and can produce cortisol (its just the HPA axis that is gubbed)

25
Q

Cushings syndrome can be caused by ACTH dependent and independent factors What is the most common cause of Cushing’s syndrome? * What are the ACTHdependent causes?

A

The commonest cause of Cushing’s syndrome is iatrogenic steroid use

ACTH dependent causes:

* Cushing’s disease (80%): pituitary tumour secreting ACTH - producing adrenal hyperplasia

* ectopic ACTH production (5-10%): e.g. small cell lung cancer

26
Q

Investigations are divided into confirming Cushing’s syndrome and then localising the lesion. A hypokalaemic metabolic alkalosis may be seen, along with impaired glucose tolerance. How is a cortisol excess established in cushing’s syndrome - what is the screening test?

A

1st line SCREENING TEST (good outpatient initial test) -

* Overnight 1mg dexamethasone (at midnight) test- measure cortisol at 8am

(there would be no cortisol suppression in Cushing’s)

24hr urinary cortisol is also a good test

27
Q

If the screening overnight dexamethasone suppression test is abnormal, what is the diagnostic test for Cushing’s syndrome?

A

If 1st line test is abnormal then carry out the 2nd line DIAGNOSTIC TEST

* Low does 48 hour dexamethasone suppression test (4mg over 48hours (0.5mg/6hr) and measure cortisol levels 6hrs after final dose

28
Q

What is the expected level of cortisol in a positive cushings low dose dexamethasone?

A

Greater than 50nmol/l

Always repeat to confirm

29
Q

ACTH dependent Cushings: * Cushing’s disease (80%): pituitary tumour secreting ACTH producing adrenal hyperplasia * ectopic ACTH production (5-10%): e.g. small cell lung cancer

If the low dose dexamethasone suppression test (4mg over 48) hours comes back with a cortisol >50nmol/l, what can be carried out to differentiate between these two causes?

A

High dose dexamethasone suppression test (2mg/6hr for 48 hours so 16mg in 48 hours)

* ACTH producing pituitary tumour will likely be suppressed by the high dose test

* Ectopic ACTH producing tumour (eg small cell lung cancer) will not be suppressed by low or high dose dexamethasone suppresion test

30
Q

Long term steroid treatment suppresses ACTH production (negative feedback to anterior pituitary) causing atrophy of adrenal cortex

Can the steroid treatment suddenly be stopped for iatrogenic cushings?

A

Cannot stop suddenly

Gradual withdrawal of steroid therapy

31
Q

How are the ACTH dependent causes of Cushing’s disease treated?

(* Pituitary tumour producing ACTH - Cushing’s disease * Ectopic ACTH production)

How adrenal adenomas causing Cushing’s treated?

A

* Cushing’ disease - The first-line treatment of Cushing’s disease is surgical resection of ACTH-secreting pituitary adenoma; this surgery involves removal of the tumor via transsphenoidal surgery (TSS)

* Ectopic ACTH production - surgery if tumour is located and hasn’t spread

Adrenal adenomas treated with adrenelectomy

32
Q

If the patient is not suitable for surgery, what are medical management options of Cushing’s disease?

A

Metyrapone or ketaconazole - these inhibit steroidgenesis (inhibit cortisol synthesis)

33
Q

> 90% hypertension cases there is no known cause (‘essential’) < 10% cases are secondary to another disorder eg. renal disease, Cushing’s Presents with hypertension and hypokalaemia

What is this?

A

Primary aldosteronism

34
Q

How do patients with Conn’s syndrome present biochemically?

A

High NaCl,

high water

Low potassium

  • presents as fatigue and muscle weakness
35
Q

Primary aldosteronism is the commonest secondary cause of hypertension

What is the commonest cause of primary aldosteronism?

A

Bilateral adrenal hyperplasia (60%)

Adrenal adenoma - Conn’s (30%)

36
Q

Diagnosing primary aldosteronism

Firstly confirm aldosterone excess 

  • Measure plasma aldosterone and renin and express as ratio (ARR-aldosterone to rennin ratio)
  •  If ratio raised then investigate further with saline suppression test

How is this measured?

A

If aldosterone levels fail to suppress by 50% with 2litres of saline, primary aldosteronism is confirmed

37
Q

When confirming the subtype of cause of primary aldosteronsim (eg bilaterl adrenal hyperplasia or adenoma), how do you carry this out?

A

 Adrenal CT to look for adenoma

 Sometimes adrenal vein sampling to confirm adenoma

38
Q

If an adenoma is found in primary aldosteronism, how is this treated?

A

Surgical

 Only if adrenal adenoma – unilateral adrenalectomy

 Cure of hypokalaemia

 Cures hypertension in 30-70% cases

39
Q

Due to the fact that bilateral adrenolectomy is not practical, what is done to treat bilateral adrenal hyperplasia?

A

Use MR (mineralocorticoid receptor) antagonists (spironolactone or eplerenone)

These are potassium sparing and decrease high blood pressure by promoting excretion of sodium and water

40
Q

What is the commonest cause of congenital adrenal hyperplasia?

A

21alpha hydroxylase deficiency (95% of cases)

41
Q

What is the classical presentation of congenital adrenal hyperplasia in males and females?

A

In males - Adrenal insufficiency

Often around two to three weeks

Poor weight gain and can presnt like addisons

In females - genital ambiguity

42
Q

How does a 21-OH deficiency cause congenital ambiguity in females when it is not involved in the pathway?

A

the enzyme difciecny prevents aldosterone and cortisol being produced, this causes a negative feedback causing more ACTH to be produced and therefore more choesterol is converted to pregnenolone

The excess pregnenolone is converted to androgens causing increased testosterone in the females

43
Q

What is the treatment of 21-OH deficiency in children?

A
  • Glucocorticoid replacement
  • Mineralocorticoid replacement in some

In adults • Control androgen excess • Restore fertility

44
Q

increased serum catecholamine’s

 Classical triad – hypertension, headache, sweating

o Rare tumour of chromaffin cells – cells of the adrenal medulla

What is this?

A

Pheochromocytoma

Also get palpitations

45
Q

Why is pheochromocytoma known as the 10% tumour?

A

 10% malignant (more common in extra-adrenal lesions)

 10% extra adrenal – called paragangliomas

 10% bilateral (up to 50% in familial cases)

 10% associated with hyperglycaemia

 10% in children

 10% familial

46
Q

What colour do chromaffin cells reduce chrome salts to?

A

Dark brown

Use potassium dichromate

47
Q

Pheochromocytoma are often missed however are an important curable form of hypertenison

What are the signs of complications?

A

Left ventricular failure

Myocardial necrosis

Stroke

Shock

Paralytic ileus of bowel

48
Q

What are the biochemical abnormalities associated with pheochromocytoma?

A

Hyperglycaemia - due to adrenaline

Mild hypercalcaemia

May have low potassium

49
Q

How is pheochromocytoma diagnosed?

A

Raised urine metanephrines for biochemical test - breakdown product of catecholamines (it has replaced catecholamines test as it is more sensitive)

Diagnosed location of the tumour by a MIBG scan and CT scan

MIBG -meta-iodobenzylguanidine scan to help locate and diagnose certain types of cancer in the body

.(these scans are taken up by sympathetic tissues - indicated functioning, eptopic and metastatic adrenal medullary tumours)

50
Q

What is the main treatment of pheochromocytomas?

A

SURGERY with pre-operative medical treatment

 alpha and beta blockade (A before B)

  • Phenoxybenzamine (alpha 1&2 blocker)
  • Propranolol, atenolol or metoprolol (B blocker)

Important the a blockade is given for b-blocker to avoid hypertensive crisis from unopposed alpha-adrenergic stimulation

51
Q

What are 5 familial conditions associated with pheochromocytomas?

A

Multiple Endocrine Neoplasia 2 (MEN2) (RET gene)

Von-Hippel-Lindau syndrome (VHL gene)

Succinate dehydrogenase mutations

Neurofibromatosis (NF1 gene)

Tuberose sclerosis (TSC1 or TSC2 gene)

52
Q

Pheochromocytoma is the commonest adrneal medulla tumour in adults What is the commonest in children?

A

Neuroblastoma

Year 2(B3) - Endocrine (35 decks)

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