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Endocrine MBCHB > Adrenal Disorders > Flashcards

Adrenal Disorders Flashcards

1
Q

What is Cushing’s disease?

A

Increased free circulating glucocorticoid

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2
Q

What is the aetiology of Cushing’s disease?

A
  • The most common cause of excess cortisol is the therapeutic administration of synthetic steroids
  • Cushing’s disease is when the increased cortisol levels are caused by a functioning pituitary adenoma, all other causes are referred to as Cushing’s syndrome

ACTH dependent

  • pituitary adenoma (68%) → Cushing’s disease
  • Ectopic ACTH (12%) - carcinoid/carcinoma e.g., lung, pancreas
  • Ectopic CRH (<1%)

ACTH independent

  • exogenous steroids
  • adrenal adenoma (10%) or carcinoma (8%)
  • adrenal cortical nodular hyperplasia (1%)
  • false positive (psuedo) - severe depression, severe alcoholism
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3
Q

What is the pathophysiology of ACTH independent Cushing’s disease?

A
  • Autonomous over-production of cortisol by the adrenal gland due to neoplasia/nodular hyperplasia
  • Adrenal enlargement in ACTH-independent disease is usually nodular
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4
Q

What is the pathophysiology of ACTH dependent Cushing’s disease?

A
  • Adrenal enlargement in ACTH-dependent disease is usually diffusePituitary adenomas (Cushing’s disease)
    • Pituitary secretes increased ACTH → increased cortisol production by adrenal gland
    Ectopic ACTH
    • Carcinoma e.g. small cell lung cancer secretes ACTH → increased cortisol production by adrenal gland
    Ectopic CRH
    • Carcinoma e.g. medullary thyroid carcinoma secretes CRH → increased ACTH by pituitary → increased cortisol by adrenal gland
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5
Q

What are the consequences of increased cortisol levels?

A
  • Protein loss
  • Altered carbohydrate and lipid metabolism
  • Excess mineralocorticoid
  • Excess androgen
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6
Q

What is the presentation of Cushing’s Disease?

A
  • Plethora (redness of the face)
  • Moon face
  • Hypertension
  • Central obesity
  • Depression/psychosis
  • Glycosuria/diabetes mellitus
  • Oedema
  • ‘Buffalo hump’
  • Oligo/amenorrhoea
  • Virilism
  • Bruising
  • Striae (purple or red)
  • Pigmentation (only occurs with ACTH-dependent causes)
  • Thin skin
  • Hirsutism
  • Acne
  • Proximal myopathy, wasting
  • Osteoporosis, fractures
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7
Q

What is characteristic of Cushing’s disease and not obesity?

A
  • Thin skin
  • Proximal myopathy
  • Frontal balding in women
  • Conjunctival oedema (chemosis)
  • Osteoporosis
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8
Q

What are the investigations for Cushing’s disease?

A
  • Overnight 1mg dexamethasone suppression test (oral) - first line
    • Normal: cortisol <50 nmol/l next morning
    • Abnormal: cortisol >130 nmol/l
  • 24hr urine free cortisol (24hr urine collection)
    • Total <250 is normal
    • Cortisol/creatinine ratio of<25 is normal
  • Diurnal cortisol variation (midnight/8am)
    • Loss of diurnal variation suspicious of Cushings
    • Serum/saliva/spot urine collection
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9
Q

How is Cushing’s disease diagnosed?

A
  • Low dose dexamethasone suppression test
    • 2 day 2mg/day dexamethasone
    • Normal: cortisol <50 nmol/l 6 hours after last dose
    • Cushing’s: cortisol >130 nmol/l
  • Repeat to confirm
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10
Q

What are the differentials for Cushing’s disease?

A
  • If serum ACTH levels are low, this suggests non-ACTH-dependent disease and adrenal imaging should be planned (CT or MRI)
  • If serum ACTH levels are high, this suggests ACTH-dependent disease and pituitary MRI should be planned as well as biochemical tests to distinguish between pituitary and ectopic ACTH (high-dose dexamethasone suppression test or exogenous CRH)
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11
Q

What is the management of Cushing’s disease?

A

Pituitary

  • Hypophysectomy (transsphenoidal route)
  • External radiotherapy if recurs
  • Last line: bilateral adrenalectomy

Adrenal Adenoma

  • Adrenalectomy

Ectopic

  • Remove source
  • OR bilateral adrenalectomy

Drug Management

  • Metyrapone given when other treatments fail or while waiting for radiotherapy to work
    • Side effects e.g. N+V common
  • Other options include ketoconazole (hepatotoxic) and pasireotide LAR (somatostatin analogue)
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12
Q

What is primary adrenal insufficiency?

A

Decreased production of adrenocortical hormones (glucocorticoids, mineralocorticoids, and adrenal androgens)

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13
Q

What is the aetiology of primary adrenal insufficiency?

A
  • Involves destruction of the entire adrenal cortex
  • Autoimmune adrenalitis is the most common cause, accounting for ~80-90% of all cases of primary adrenal insufficiency
    • May be part of wider autoimmune syndromes e.g. autoimmune polyglandular syndrome (APS)
    • Associated with other autoimmune diseases - T1DM, autoimmune thyroid disease, pernicious anaemia
  • Infectious adrenalitis - TB, CMV disease, HIV
  • Metastatic malignancy - lung, breast
  • Adrenal haemorrhage
    • Septicaemic infection - Waterhouse-Friderichsen syndrome
    • Disseminated intravascular coagulation (DIC)
    • Anticoagulation treatment
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14
Q

What is the pathophysiology of primary adrenal insufficiency?

A
  • Decreased mineralocorticoids
    • K+ retention, Na+ loss
    • Hyperkalaemia, hyponatraemia, volume depletion and hypertension
  • Decreased glucocorticoids → hypoglycaemia
  • Excess pigmentation reflects excess ACTH from pituitary
    • ACTH molecule contains sequence for MSH within it
    • ACTH is degraded by proteases eventually exposing MSH
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15
Q

What is the presentation of primary adrenal insufficiency?

A
  • Signs and symptoms occur once >90% of the gland has been destroyed
  • Vague symptoms - weakness, fatigue, anorexia, N+V, weight loss, diarrhoea, dizziness and low BP, abdominal pain
  • Skin pigmentation (raised POMC) - not seen in hypopituitarism
    • Look ‘tanned’, as well as black spots in buccal mucosa, dark palmar creases and dark finger spaces
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16
Q

What are the investigations for primary adrenal insufficiency?

A
  • Adrenal autoantibodies positive in 70%
  • Biochemistry - ↓ Na+, ↑ K+, may be hypoglycaemia (especially in paediatrics)
  • Short synacthen test
    • Measure plasma control before and 30 mins after IV/IM ACTH injection
    • Normal: baseline >250 nmol/L, post ACTH >550 nmol/L
  • ACTH levels very high (results in skin pigmentation)
  • Renin/aldosterone levels - ↑↑ renin, ↓ decreased aldosterone
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17
Q

What is the management of primary adrenal insufficiency?

A

Pharmacological Management

  • Hydrocortisone as cortisol replacement
    • If unwell IV first
    • Usually 15-30mg PO daily in divided doses
    • Try and mimic diurnal rhythm (higher dose in morning)
  • Fludrocortisone as aldosterone replacement
    • Careful monitoring of BP and K+

Education

  • ‘Sick day rules’ - increase steroid replacement when unwell or undergoing other stress e.g. preoperative
  • Cannot stop suddenly or risk adrenal crisis
  • Need to carry identification - emergency steroid card, alert to long term steroid treatment bracelet
  • There are rules for medical professionals regarding steroid management for interventions/surgery (usually require increased dose)
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18
Q

What is secondary adrenal insufficiency?

A

lack of production of ACTH by the pituitary gland

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19
Q

What is tertiary adrenal insufficiency?

A

lack of CRH secretion by the hypothalamus

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20
Q

What is the aetiology of secondary/tertiary adrenal insufficiency?

A
  • Iatrogenic (excess exogenous steroid) - inhibit CRH production and ACTH production, adrenal gland becomes atrophied and is unable to produce cortisol even acutely when ACTH is given endogenously
  • Pituitary/hypothalamic disorders - tumours, surgery and radiotherapy
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21
Q

What is the presentation of secondary/tertiary adrenal insufficiency?

A

Similar to Addison’s except:

  • Skin pale (no ↑ ACTH)
  • Aldosterone production intact (regulated by RAAS)
    • No hypertension
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22
Q

What is the investigation for secondary/tertiary adrenal insufficiency?

A
  • Insulin tolerance test
  • CRH stimulation test
  • MRI
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23
Q

What is the management of secondary/tertiary adrenal insufficiency?

A

Treat with hydrocortisone replacement (fludrocortisone unnecessary)

24
Q

What is adrenal adenoma?

A

Benign neoplasm emerging from the cells of the adrenal cortex

25
Q

What is the aetiology of adrenal adenoma?

A

found in almost all age groups but increase in frequency with age

26
Q

What is the pathophysiology of adrenal adenoma?

A
  • majority (~95%) are non-functioning and asymptomatic
  • well circumscribed, encapsulated lesions
  • solitary, small (2 to 3cm), bright yellow (Lipid) and buried within the gland - do not cause a mass lesion
27
Q

What are the histological features of adrenal adenoma?

A
  • composed of cells resembling adrenocortical cells
  • well-differentiated, small nuclei
28
Q

What is the presentation of adrenal adenoma?

A
  • often incidental finding during abdominal imaging
  • patients with hyperfunctioning adrenal gland adenomas present with manifestations of excess hormone secretion e.g., Cushing’s, Conn Syndrome
29
Q

What are the investigations for adrenal adenoma?

A
  • imaging (CT, MRI)
  • Hormonal testing
30
Q

What is the management of adrenal adenoma?

A
  • a small adrenal lesion with typical features of an adenoma and without biochemical abnormality can be safely left in situ
  • Surgical excision required if:
    • functioning lesion
    • large lesion (>3-5cm) as considered potentially malignant
31
Q

What is primary hyperaldosteronism?

A

Autonomous production of aldosterone independent of its regulators (angiotensin II/potassium)

32
Q

What is the aetiology of primary hyperaldosteronism?

A

Adrenal Adenoma (Conn’s syndrome):

  • ~30% cases
  • Do not suppress ACTH - adjacent and contralateral adrenal tissue is not atrophic

Bilateral adrenal hyperplasia:

  • Idiopathic
  • Accounts for ~60% cases

Rare Causes:

  • Genetic mutations - several familial forms of hyperaldosteronism recognised as well as recurrent somatic mutations observed in sporadic cases
  • Unilateral hyperplasia
33
Q

What are the genetic factors related to adrenal adenoma and primary hyperaldosteronism?

A
  • KCNJ5 channel is a rectifying selective channel which maintains membrane hyperpolarisation
  • Mutations lead to loss of ion selectivity; Na+ entry and depolarisation and therefore increased aldosterone production
34
Q

What is the pathophysiology of primary hypoaldosteronism?

A
  • Commonest secondary cause of hypertension

Cardiac actions of aldosterone:

  • Increased cardiac collagen
  • Cytokines and ROS synthesis
  • Increased sodium retention
  • Abnormal endothelial function
  • Increased sympathetic outflow
  • All contribute to increased BP, LVH and atheroma
35
Q

What is the presentation of hyperaldosteronism?

A
  • Significant hypertension
  • Hypokalaemia (~30%)
  • Alkalosis
36
Q

What are the investigations for primary hyperaldosteronism?

A

Confirm aldosterone excess

  • Measure plasma aldosterone: renin ratio
  • If ratio raised investigate further with saline suppression test
    • Failure of plasma aldosterone to suppress by > 50% with 2 litres of normal saline confirms PA

Confirm subtype

  • Adrenal CT to demonstrate adenoma
  • Sometimes adrenal vein sampling to confirm adenoma is true source of aldosterone excess
37
Q

What is the management of primary hyperaldosteronism?

A

Adrenal adenoma

  • Unilateral laparoscopic adrenalectomy
  • Cures hypokalaemia
  • Cures hypertension in 30-70% of cases

Bilateral adrenal hyperplasia

  • Mineralocorticoid receptor antagonists - spironolactone or eplerenone
38
Q

What is secondary hyperaldosteronism?

A

Increased adrenal production of aldosterone in response to nonpituitary, extra-adrenal stimuli such as renal hypoperfusion

39
Q

What is the aetiology of secondary hyperaldosteronism?

A
  • Reduced renal blood flow leads to excess renin (and hence angiotensin II)
  • Causes of reduced renal blood flow include:
    • Obstructive renal artery disease (e.g., atheroma, stenosis)
    • Renal vasoconstriction (as occurs in accelerated hypertension)
    • Oedematous disorders (e.g., heart failure, cirrhosis with ascites)
40
Q

What is the presentation of secondary hyperaldosteronism?

A

Hypertension

41
Q

What are the investigations of secondary hyperaldosteronism?

A
  • Renin/aldosterone ratio - high aldosterone and high renin indicates secondary hyperaldosteronism
  • Doppler ultrasound, CT angiogram or magnetic resonance angiography (MRA) to look for renal artery stenosis or obstruction
42
Q

What is the management of secondary hyperaldosteronism?

A
  • Aldosterone antagonists e.g., spironolactone
  • Treat underlying cause e.g., percutaneous renal artery angioplasty via the femoral artery to treat in renal artery stenosis
43
Q

What is phaeochromocytoma?

A

Catecholamine-secreting tumour that typically derived from chromaffin cells of the adrenal medulla

44
Q

What is the aetiology of phaeochromocytoma?

A
  • 10% (up to 30%) are extra-adrenal → paragangliomas
    • Occur elsewhere in the sympathetic chain - typically occur in the head and neck but are also found in the thorax, pelvis and bladder
    • More closely associated with genetic associations than phaeochromocytoma
  • 10% are bilateral (up to 50% in familial cases)
  • 10% are biologically malignant (metastasis)
    • More common (20-40%) in paragangliomas
  • 10% are NOT associated with hypertension
  • 25% are familial
45
Q

What are the familial risk factors for phaeochromocytoma?

A
  • Germline mutations in one of several known pre-disposing genes including neurofibroma type 1, RET (MEN2), VHL, succinate dehydrogenase enzymes and tuberous sclerosis
  • Younger presentation, more often bilateral
  • More often malignant if associated with germline mutation of B unit of succinade dehydroxinate
46
Q

What is the pathophysiology of phaeochromocytoma?

A
  • Secrete catecholamines
  • Rare cause of secondary hypertension

Spread

  • Propensity for skeletal metastasis
  • Other sites include regional lymph nodes, liver and lung
47
Q

What is the presentation of phaeochromocytoma?

A
  • Insidious onset in most patients
  • 10% have no symptoms of adrenal disease

Symptoms

  • Classical triad (up to 90% of cases) - hypertension, headache, sweating
  • Paroxysmal sweating, headache, anxiety
    • Episodes triggered by stress, exercise, posture, palpation of the tumour
  • Paraganglioma of the bladder associated with micturition during episodes
  • Weight loss

Signs

  • Hypertension (50% paroxysmal, 50% persistent)
  • Postural hypotension in 50% of cases
  • Pallor
  • Tachycardia, paradoxical bradycardia
  • Pyrexia
48
Q

What are the investigations for phaeochromocytoma?

A

Lab Tests

  • 2 x 24 hr catecholamines or metanephrines
    • 7% of phaeochromocytomas had normal 24 hr urinary catecholamines - secretion is episodic so take samples when patient symptomatic
  • Plasma metanephrines, ideally at time of symptoms

Other biochemical abnormalities

  • Hyperglycaemia
  • May be low K+
  • High haemocrit (raised Hb concentration)
  • Mild hypercalcaemia
  • Lactic acidosis - in absence of shock

Imaging

  • MRI - abdomen or whole body
  • MIBG scan
  • PET scan
49
Q

What is the management of phaeochromocytoma?

A

Pre-operative Management

  • Full ⍺-blockade (phenoxybenzamine), when stable full β-blockade (propranolol, atenolol or metoprolol)
  • Fluid and/or blood replacement
  • Anaesthetic assessment

Definitive treatment

  • Laparoscopic surgery
    • Total excision where possible
    • Tumour de-bulking if unlikely to be cured by surgery - reduces excess hormone production
  • Chemotherapy if malignant, consider radio labelled MIBG

After surgery

  • Long-term follow-up
  • Genetic testing and family tracing and investigation
    • Patients with known Phaeo predisposition genes should undergo periodical clinical, biochemical and radiological evaluation to facilitate the early detection of tumours
50
Q

What are the complications of phaeochromocytoma?

A
  • Cardiac failure, infarction, arrhythmias
  • CVA
51
Q

What is congenital adrenal hyperplasia?

A

Inherited group of disorders characterised by a deficiency in one of the enzymes necessary for cortisol synthesis

52
Q

What is the aetiology of congenital adrenal hyperplasia?

A

90% due to an autosomal recessive 21⍺-hydroxylase deficiency

53
Q

What is the pathophysiology of congenital adrenal hyperplasia?

A
  • 21⍺-hydroxylase deficiency prevents the production of aldosterone and cortisol
  • Increased volume of precursors will be diverted into the androgen pathway → increased testosterone and dihydrotesterone
  • Reduced cortisol stimulates ACTH release and cortical hyperplasia
  • Other enzyme deficiencies will result in varied clinical features depending on the pathway affected (e.g. adrenal insufficiency with no signs of reduced aldosterone or vice versa)
54
Q

What is the presentation of congenital adrenal hyperplasia?

A

Classic CAH

  • Presents at birth or shortly after
  • Genital ambiguity (virilisation) in females
  • Adrenal failure - collapse, hypotension, hypoglycaemia, poor weight gain
    • Biochemical patten of Addison’s disease

Non-Classic CAH

  • Partial 21⍺-hydroxylase deficiency
  • Presents later (adolescence/adulthood)
    • Precocious puberty
    • Hirsutism
    • Acne
    • Oligomenorrhoea, infertility or sub-fertility
55
Q

What are the investigations of congenital adrenal hyperplasia?

A
  • Basal (or stimulated) 17-OH progesterone
  • Genetic analysis
56
Q

What is the management of congenital adrenal hyperplasia?

A

Paediatrics

  • Glucocorticoid replacement
  • Mineralocorticoid replacement in some
  • Surgical correction
  • Achieve maximal growth

Adults

  • Glucocorticoid replacement, avoiding steroid over-replacement
  • Control androgen excess
  • Restore fertility

Endocrine MBCHB (13 decks)

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