Clinical Aspects of Adrenal Disorders Flashcards
What does each layer of the adrenal glands secrete?
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What are the classification of adrenal disorders?
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Explain the common approach to treating adrenal disorders?
- Clinical suspicion
- Test for assessing functional status
- Is it functioning
- Is it primary or secondary
- What is the aetiology
- If tumour
- Can it be removed
- Would chemotherapy and radiotherapy help
Endocrine deficiency needs correction
What does HPA stand for?
Hypothalamus-pituitary-adrenal axis
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What impact does hypofunction have on the HPA?
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What can hypofunction of the adrenal glands be caused by?
- Primary adrenal insufficiency
- Addison’s disease
- Immune destruction
- Invasion
- Infiltration
- Infection
- Infarction
- Iatrogenic
- Adrenal enzyme defect
- Congenital adrenal hyperplasia (most commonly 21-hydroxylase deficiency)
- Addison’s disease
What are some causes of Addison’s disease?
Immune destruction
Invasion
Infiltration
Infection
Infarction
Iatrogenic
What enzyme most commonly causes adrenal enzyme defect?
21-hydrolase deficiency
What does adrenal enzyme defect cause?
Congenital adrenal hyperplasia
What autoantibodies are looked for in Addison’s disease?
Positive adrenal autoantibodies to 21-hydroxylase
How is the adrenal cortex involved in Addison’s disease?
Lymphatic infiltrate of adrenal cortex
Addison’s disease is often associated with other autoimmune disease, what are some examples?
Thyroid disease
Type 1 diabetes mellitus
Premature ovarian failure
What are some common symptoms of primary adrenal failure?
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What are some clues to a diagnosis of adrenal failure?
- Disproportion between severity of illness and circulatory collapse/hypotension/dehydration
- Unexplained hypoglycaemia
- Other endocrine features (hypothyroidism, body hair loss, amenorrhoea)
- Previous depression or weight loss
What is the most common cause of adrenal failure?
Autoimmune Addison’s disease
What is done to diagnose adrenal insuffiency?
Routine bloods (U and Es, glucose, FBC)
Random cortisol
Synacthen test (and basal ACTH)
What routine bloods are done when investigating adrenal insuffiency?
U and Es
Glucose
FBC
For a random cortisol test, what level is not an Addison’s diagnosis?
>550nmol/L
For a random cortisol test, what level is potentially an Addison’s diagnosis?
<500nmol/L
Is Addison’s disease a cause of hyper or hyposecretion of the adrenal glands?
Hyposecretion
What is the synacthen test?
Special chemical test to see how well adrenal glands make cortisol
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Explain the process of diagnosing adrenocortical insuficiency?
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What medicines can be used as glucocorticoid replacement?
- Hydrocortisone 20-30mg
- Prednisolone 7.5mg
- Dexamethasone 0.75mg
What can be used as mineral corticoid replacement?
Synthetic steroid called fludrocortisone
What does fludrocortisone bind to?
Aldosterone receptors
When prescribing people steroids, who needs special care?
- Hypoadrenal patients on replacement steroids
- Patients on steroids in doses sufficient to suppress the pituitary adrenal axis (>7.5mg prednisolone daily or equivalent)
- Patients who have received such treatment during the previous 18/12
What action should be taken for people you have prescribed steroids too who are now suffering from a minor short lived illness or stress?
Double glucocorticoid dose
What action should be taken for people you have prescribed steroids too who are now suffering from a major illness or operation?
- 100mg hydrocortisone IV stat
- 50-100mg HC IV 8-hourly
What are 3 important self-care rules for patients on steroids?
- Never miss steroid dose
- Double the hydrocortisone dose in the event on intercurrent illness (such as flu or UTI)
- If severe vomiting or diarrhoea call for help without delay
What are some endocrine causes of hypertension?
- Primary hyperaldosteronism
- Unilateral adenoma
- Bilateral hyperplasia
- Rarer causes
- Phaeochromocytoma
- Cushing’s syndrome
- Acromegaly
- Hyperparathyroidism
- Hypothyroidism
- Congenital adrenal hyperplasia
What are some causes of hypersecretion of adrenal glands?
- Cortex
- Cushing’s syndrome (cortisol, androgens)
- Adenoma, carcinoma or bilateral hyperplasia
- Conn’s syndrome (aldosterone)
- Adenoma or bilateral hyperplasia
- Cushing’s syndrome (cortisol, androgens)
- Medulla
- Phaeochromocytoma
What does Cushing’s syndrome cause hypersecretion of?
Cortisol, androgens
What does Conn’s syndrome cause hypersecretion of?
Aldosterone
What are some causes of primary Cushing’s syndrome?
Adenoma, carcinoma or bilateral hyperplasia
What are some causes of primary Conn’s syndrome?
Adenoma or bilateral hyperplasia
What is a cause of hypersecretion from the adrenal medulla?
Phaeochromocytoma
What is the clinical presentation of Cushing’s syndrome?
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What are some ACTH dependent causes of Cushing’s syndrome?
- Pituitary tumour (Cushing’s disease)
- 75% of cases
- Ectopic ACTH secretion (such as lung carcinoid)
- 5% of cases
What are some ACTH indendent causes of Cushing’s syndrome?
Explain the approach to hypercortisolism?
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What are some examples of screening tests for Cushing’s syndrome?
- 24 hour urinary free cortisol
- Normal 14-135nmol/24 hour
- 1mg overnight dexamethasone suppression test taken at midnight
- Normal <50nmol/L at 9am
How do levels of cortisol and ACTH normally compare?
Concentration levels mimic each other over the course of the day
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What is Conn’s syndrome also known as?
Primary aldosteronism
What does RAAS stand for?
renin-angiotensin-aldosterone system
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What system is involved in the pathophysiology of primary hyperaldosteronism (Conn’s disease)?
RAAS
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Explain the pathophysiology of Conn’s syndrome?
Aldosterone producing tumour causes increased blood volume, blood pressure and urine potassium
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What is used to screen for Conn’s syndrome?
Aldosterone to renin ratio?
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What is the cut off for the aldosterone to renin ratio for primary hyperaldosteornism?
Ratio >20
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What does it mean if aldosterone to renin ratio is <20?
Secondary hyperaldosteronism
Essential hypertension
(not primary hyperaldosteronism)
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What does PRA stand for?
Plasma renin activity
What does PAC stand for?
Plasma aldosterone concentration
What are causes of increased plasma renin activity (PRA) and increased plasma aldosterone concentration (PAC)?
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What are causes of decreased plasma renin activity (PRA) and increased plasma aldosterone concentration (PAC)?
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What are causes of decreased plasma renin activity (PRA) and decreased plasma aldosterone concentration (PAC)?
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Explain what happens after clinical suspicion of hyperaldosteronism to diagnose it?
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What screening test are done after clinical suspicion of hyperaldosteronism?
Plasma renin activity (PRA)
Plasma aldosterone concentration (PAC)
Look at PAC/PRA ratio, >20 means primary aldosterone
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What is a confirmatory test for hyperadosteornism?
24 hour urine aldosterone
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What investigations are done to establish the aldosterone source in hyperaldosteronism?
CT scan of adrenal glands
Upright posture test
Plasma 18-hydroxycorticosterone
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What is phaeochromocytoma?
Rare tumour of adrenal gland tissue that causes release of epinephrine and norepinephrine
What does phaeochromocytoma cause the hypersecretion of?
Epinephrine and norepinephrine
What is the clinical presentation of phaeochromocytoma?
- Hypertension
- Paroxysmal attacks
- Headache
- Sweating
- Palpitations
- Tremor
- Pallor
- Anxiety
Is phaeochromocytoma possible due to inherited origin?
30% of the time
What genes and familial syndromes are responsible for genetic phaeochromocytoma?
- Genes
- RET, VHL
- Familial syndromes
- MEN2
Explain the process of investigating an adrenal mass?
1) Clinical suspicion
2) Endocrine workout
- Free metanephrine in plasma or urine
- ALD/PRA ratio
3) Imaging work up
- CT
- Chemical shift MRI
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What is congenital adrenal hyperplasia most often due to?
In >90% of cases is due to 21-hydroxylase deficiency
What do severe cases of congenital adrenal hyperplasia cause?
Neonatal salt crises
Ambiguous genitalia (girls)