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HPA Axis disorders Flashcards

1
Q

What hormones are released by the anterior pituitary gland?

A

TSH
ACTH
FSH and LH
GH
Prolcatin

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2
Q

What hormones are released by the posterior pituitary gland?

A

Oxytocin
ADH

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3
Q

What is the main blood supply to the adrenal gland?

A

Superior adrenal artery - from the inferior phrenic artery
Middle adrenal artery - abdominal aorta
Inferior adrenal artery - from renal arteries

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4
Q

What is the main venous drainage of the adrenal gland?

A

Right adrenal vein into the IVC
Left adrenal vein into the left renal vein

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5
Q

What are the different layers of the adrenal gland?

A

Capsule
Cortex =
Zone glomerulosa
Zona fasciculata
Zona reticularis
Medulla

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6
Q

What does each section of the adrenal cortex secrete?
What is the basic function of this?

A

Zona glomerulosa - mineralcorticoids - salt - inc blood pressure
Zona fasiculata - corticosteroids (some androgens) - sugar - stress and inc bg
Zona reticularis - androgens (some corticosteroids) - sex - sexual development

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7
Q

What does the medulla of the adrenal gland do?

A

has chromaffin cells which secrete catecholamines - flight or fight response
Also secrete enkephalins - pain control

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8
Q

What is the adrenal axis? (HPA)

A

Hypothalamus releases CRH
Stimulates anterior pituitary to release ACTH
Stimulates adrenal glands to release cortisol
Cortisol has negative feedback effect to suppress CRH + ACTH

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9
Q

What is cortisol?
Where is it produced?
Trends in levels?

A

A steroid hormones - glucocorticoid - released from zona fasiculata of adrenal gland in response to stress and hypoglycemia.
Diurnal variation - peaks in mornings, lowest in evenings

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10
Q

What are the different actions of cortisol within the body?

A

Increase alterness
Inhibits bone formation
Raises blood glucose
Inhibits immune system
Increases metabolism
Anti-inflammatory effects

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11
Q

Give an overview of the Renin-Angiotensin-Aldosterone system

A

JG cells - in afferent arterioles in the kidney release enzyme renin in response to low BP
Converts angiotensinogen (liver) to angiotensin 1.
ACe (lungs) converts to angiotensin 2
Angiotensin 2 = vasoconstriction = inc BP
Angiotensin 2 = stimulates the release of aldosterone from adrenal glands

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12
Q

What are the effects of aldosterone in the nephron?

A

Increase Na+ reabsorption from the distal tubule
Increase K+ secretion from distal tubule
Increase H+ secretion from the collecting duct
Water follow sodium by osmosis - leading to increased intravascular volume and inc BP

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13
Q

What electrolyte abnormality is seen in aldosterone receptor antagonists?

A

Hyperkalemia

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14
Q

What are the two types of corticosteroids?

A

Glucorticoids e.g cortisol
Mineralcorticoids e.g aldosterone

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15
Q

What is the function of glucorticoids?

A

Increase alertness
Anti-inflammatory
Inhibits immune system
Inhibits bone formation
Raises blood glucose
Increases metabolism

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16
Q

What are the effects of mineral corticoids?

A

Increase intravascular volume to increase blood pressure
Causes sodium to be adsorbed and potassium to be excreted.

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17
Q

Give some examples of synthetic corticosteroids and where they sit on the glucorticoids/mineralcorticoid spectrum

A

Mainly gluc some mineral - prednisolone
50/50 = hydrocortisone
Fully gluc -dexamethosome, beclometasone
Fully mineral with some gluc - fludrocortisone

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18
Q

How can we reduce the adverse effect of chronic use of systemic steroids?

A

Avoid oral preparation whre possible
Use lowest effective dose for the shortest amount of time
Optimise and pre-existing co-morbidities
Monitor patients for adverse effects
Add a PPI for patients also receiving NSAIDs/Anti-coagulants
Doses should always be tapered down rather than stopped abruptly

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19
Q

At what stage of use do steroid become dangerous?

A

> 5mg pred for 4w+ - risk of HPA axis suppression and adrenal crisis if physiologically stressed
Short erm use increase 30 day risk of sepsis, VTE and fractures

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20
Q

How do exogenous steroids affect the HPA axis?

A

Mimic endogenous cortisol - act as negative feedback signal to reduce ACTH secretion
Less stimulation of adrenal gland so less endogenous cortisol
Persistent suppression leads to adrenal gland atrophy -> unable to produce adequate cortisol even after exogenous source has been removed = adrenal insufficiency

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21
Q

What are the sick day rules for steroids?

A

During acute physiological stress (infection or surgery)
Long term steroid dose should be increases
To meet increased requirements of body - adrenal gland suppressed so not able to produce

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22
Q

What are the side effects of long term corticosteroid use?

A

Cataracts
Ulcers
Skin thinning/brusing, straie
HTN
Infection - oral thursh
Necrosis of the femoral head
Glucose elevation
Osteoporosis/obesity
Immunosuppression and impaired wound healing
Depression/mood changes

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23
Q

Define adrenal insufficiency

A

When the adrenal glands do not produce enough steroid hormones - cortisol and aldosterone

may also affect androgens and catecholamines

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24
Q

What are the risk factors for adrenal insufficiency?

A

Female
Autoimmune disease
Hyper-coagulable states
Adrenal haemorrhage (warfarin and DOACs)

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25
What is the common presentation of adrenal insufficiency?
Fatigue Muscle Weakness Dizziness and Fainting Muscle cramps Thirst and craving salts Weight loss Abdominal pain Depression Reduced libido Loss of pubic hair Hypotension Hypoglycemia Hyponatremia, hyperkalemia
26
What are some signs that can occur in adrenal insufficiency?
Postural hypos Bronze hyperpigmentation of the skin (skin creases and the oral mucosa) - ACTH stimulates melanocytes
27
What are the key clinical features of addisons disease?
Bronze pigmentation of the skin Changes in distribution of body hair GI disturbances Weakness Weight loss Postural Hypos Hypoglycemia
28
What are the signs of an adrenal crisis?
Profound fatigue Dehydration Vascular collapse decreases BP Renal shutdown - decreased serum Na and inc Serum K
29
What are the primary causes of adrenal insufficiency?
Damaged adrenal glands - cortisol and aldosterone mostly affected Autoimmune (70%) - addisons disease Infections Medications Metastatic Adrenal Haemorrhage Familial Infiltrative diseases
30
What is meant by central adrenal insufficiency?
Secondary and tertiary causes (aka not the adrenal gland)
31
What are the secondary causes of adrenal insufficiency?
Tumours - pituitary adenoma Surgery to pituiary radiotherapy Sheehans syndrome Trauma Mechanism: Damage to the pituitary gland Inadequate ACTH secretion Less stimulation of adrenals Less cortisol produced
32
What are the causes of tertiary adrenal insufficiency?
Usually long term corticosteroid causes suppression of the hypothalamus Abrupt stop of exogenous steroids - hypothalamus remains suppressed
33
What is a key difference between peripheral and central adrenal insufficient?
Peripheral - low cortisol and aldosterone Central - low cortisol only, aldosterone remains normal as the RAAS system is not affected by the Hypothalamus or pituitary gland
34
How can blood tests be used to differentiate between primary, secondary and tertiary adrenal insufficiency?
Primary - low cortisol, high ACTH, renin high, aldosterone low Secondary - low cortisol, low ACTH, high CRH, renin normal, aldosterone normal Tertiary - low cortisol, low ACTH, low CRH
35
What bedside investigations should be done for suspected adrenal insufficiency?
Lying standing BP Capillary blood glucose
36
How bloods should be done for suspected adrenal insufficiency?
Na+ = low K+ = high Urea and creatinine = raised Morning cortisol - falsely normal ACTH, Renin, cortisol, aldosterone
37
What auto-antibodies are present in Addison's disease?
Adrenal cortex Ab 21-hydroxylase Ab
38
What imaging may be done in suspected adrenal insufficiency?
CT/MRI of the adrenal glands MRI - pituitary - not routine
39
What special test should be done in suspected adrenal insufficiency?
Short synACTHen test
40
What happens in the short synACTHen test?
1. Baseline serum cortisol 2. give synthetic ACTH (synacthen) 3. Repeat cortisol 30 mins If cortisol >420nmol/L indicates adequate adrenal gland response If less - primary adrenal insufficiency.
41
What is a common source of ectopic ACTH secretion?
small cell lung cancer - neuroendocrine cells - paraneoplastic syndrome
42
What is the management of adrenal insufficiency?
Replacement steroids: Hydrocortisone - replace cortisol Fludrocortisone - replace aldosterone Steroid ID card, ID tag, emergency letter to alert emergency services Sick day rules education Emergency IM hydrocortisone supply with patient education
43
What is an adrenal (addisonian) crisis)? How does it present?
Life-threatening - severe adrenal insufficiency May be first presentation or triggered by infection/trauma Present - reduced consciousness, severe hypotension, hypoglycemia, hyponatremia, hyperkalemia
44
How do you manage adrenal (addisonian) crisis?
ABCDE - treat as appropriate IM/IV hydrocortisone 100mg stat followed by infusion or 6hrly doses IV fluid resus Correct hypoglycemia Monitor electrolytes and fluid balance
45
What is the relevant epidemiology of Addisons disease?
peak 30 to 40yrs Twice as common in females
46
What acid-base abnormality commonly occurs in Addisons disease?
Metabolic acidosis
47
What are the major aetiologies of addisons disease + primary adrenal insufficiency?
Autoimmune adrenalitis - destruction of the adrenal cortex, isolated or part of a syndrome Infection - TB, fungal, HIV and cytomegalovirus Genetic disorders - CYP21A2 - congenital adrenal hyperplasia, AIRE. Metastatis infiltartions - lungs, breast or melanoma mets Adrenal haemorrhage Medication - prolonged glucocorticoids (suppress HPa axis)
48
What are some important differential diagnosis for Addisons disease?
1. insufficiency secondary to pituitary disease - hyperpigmentation does not occur, and aldosterone levels tend to be preserved. 2. Adrenal TB -also have fever and night sweats, adrenal calcification 3. Sepsis - acute adrenal dysfunction, hypotensive
49
What are some common complications of Addisons disease?
Adrenal crisis = severe hypotension, hypoglycemia, altered mental status Chronic - fatigue, weight loss, electrolyte imbalances Osteoporosis - from long term glucorticoids Infections - increased susceptibility due to impaired immune function, prompt recognition and treatment is required
50
What is the most common cause of secondary HTN?
Hyperaldosteronism Presents in up to 10% of patients
51
When should hyperaldosteronism by tested for as a cause of HTN?
Younger (under 40yrs) Fail to respond to treatment Low potassium (may still be normal)
52
How does hyperaldosteronism present?
Headache Muscle weakness Fatigue Resistant hypertension Signs of hypokalemia = cardiac arrhythmias (and muscle weakness) Metabolic alkalosis = vomiting, nausea, light-headed or confused. Polyuria and polydipsia.
53
What are the different causes of primary hyperaldosteronism? What is it?
Adrenal glands too much aldosterone, inc BP, decrease renin Bilateral adrenal hyperplasia (most common) Adrenal adenoma secreting aldosterone (Conn's syndrome) Familial hyperaldosteronism (rare)
54
What is secondary hyperaldosteronism? what are the common causes?
Excessive renin stimulates the release of axcessive aldosterone -> caused by disproportionately low BP in the kidneys Renal artery stenosis (atherosclerosis) Heart Failure Liver cirrhosis and ascities
55
What bedside investigations should be done for hyperaldosteronism?
Blood pressure ECG
56
What bloods should be done for hyperaldosteronism?
K+ = low Na+ = raised/normal Blood gas - metabolic alkalosis (raised bicarb) Serum aldosterone Aldosterone to renin ratio = primary high aldo and low renin, secondary high aldosterone and high renin
57
What imaging should be done for hyperaldosteronism?
CT/MRI of the adrenal gland - hyperplasia or tumour Renal artery imaging (Doppler, CT angiogram, MR-angiograpghy) for renal artery stenosis
58
What special tests may be done in hyperaldosteronism?
Adrenal vein sampling Taking blood for both adrenal veins to locate which side is producing more aldosterone.
59
What is the treatment for hyperaldosteronism?
Eplerenone and spironolactone - aldosterone antagonists Treatment of the underlying causes: - surgical removal of adrenal adenoma - percutaneous renal artery angioplasty via the femoral artery to treat renal artery stenosis.
60
What is the relevant epidemiology of primary hyperaldosteronism?
Peak incidence of 40-50yrs Equal between men and women
61
What is the relevant pathophysiology of hyperaldosteronism?
Excessive secretion of aldosterone from the adrenal cortex - independently of the RAAS system Acts on mineralcorticoid receptors in distal tubles and CD of kidney - inc Na+ reabsorption and potassium secretion Net effect is water retention leading to increased blood volume (HTN and fluid retention) and hypertension - hypokalemia. Activates PANS due to hypertension - bradycardia and low CO - however insufficient to compensate for high BP. Renin suppressed
62
What is the first line investigation for primary hyperaldosteronism?
Aldosterone/renin ratio
63
What are some important differentials for primary hyperaldosteronism?
Secondary - normal renin Cushing - central obesity, moon facies, purple striae and hirsutism Pheochromocytoma - episodic headaches, diaphoresis, palpitations.
64
Define cushing syndrome /cushing disease
Prolonged high levels of glucorticoid (cortisol) in the body
65
What is the difference between Cushing syndrome and crushing disease?
Cushing syndrome = clinical manifestation of pathological hypercortisolism Cushing disease = pituitary adenoma, secreting excessive ACTH, thus stimulating excess cortisol release from adrenal glands/
66
What are the two forms of Cushings?
Exogenous or iatrogenic = medication or substance containing cortisol Endogenous = body produced too much cortisol
67
What are the three forms of endogenous cushing?
Cushing disease - pituitary tumour (adenoma most common) secrete ACTH Ectopic - paraneoplastic syndrome - ACTH released from small cell lung cancer or pancreatic cancer Adrenal gland - tumour/hyperplasia
68
What is the relevant epidemiology of Cushing disease?
Rare Affect 10-15 people per million every year More common in women People aged 20-50yrs.
69
What is a key sign of ACTH elevation?
Hyperpigmentation Stimulates melanocytes to produce melanin
70
What are some physiological causes of hypercortisolism?
Physical stress Malnutrition Alcoholism Depression Pregnancy Metabolic syndrome
71
What are the different metabolic effects of Cushing syndrome?
Hypertension Cardiac hypertrophy Type 2 Diabetes Dyslipidaemia Osteoporosis
72
What is the general presentation of Cushing syndrome?
Enlarged fat pad 'buffalo hump) Insomina Anxiety and depression Limb wasting Easy bruising Abdominal striae Central obesity Hirsutism Round 'moon' face
73
What bedside investigation should be done for Cushing syndrome?
24hr urinary free cortisol Capillary blood glucose
74
What bloods should be done for Cushing syndrome investigations?
FBC - raised WCC U&Es - low K+ if adrenal adenoma also secreting aldosterone ACTH serum level Morning cortisol
75
What imaging should be done for Cushing syndrome investigation?
MRI for brain pituitary adenoma CT chest for small cell lung cancer CT abdomen for adrenal tumours
76
What special tests should be done for suspected Cushing syndrome?
Dexamethasone suppression test Diagnose endogenous cushing syndrome Normal - dex suppress cortisol due to negative feedback on the HPA axis Lack of cortisol suppresion = Cushing syndrome
77
What are the different types of dexamethosone suppresion test? How does this help diagnose the type of Cushings?
All detect endogenous cushings 1. Low dose overnight - lack of suppresion = cushing 2. Low does 48hr test - lack of suppresion = cushing 3. High dose 48hr test - higher dose can suppress Cushing disease (Pituitary adenoma) but not adrenal adenoma or ectopic ACTH.
78
What are the common complications of Cushing Syndrome?
Hypertension Osteoporosis Fractures Stroke Diabetes Mellitus Frequent infections Heart attack Thromboembolism
79
What is the typical surgical treatment for Cushing syndrome?
Trans-sphenoidal resection of pitutary tumour Surgical removal of adrenal tumour Surgical removal or paraneoplastic tumour e.g SCLC Bilateral adrenalectomy - followed by lifelong steroid replacement therapy
80
What medication may be given to help treat Cushing syndrome?
Metyrapone - reduce production of cortisol in the adrenals Ketoconazole - steroidogenic inhibitor - endogenous disease. LOW CONCERN
81
What is Nelsons syndrome?
Development of an ACTH producing pituitary tumour following bilateral adrenalectomy Due to lack of cortisol negative feedback Causes: Skin pigmentation Bitemporal hemianopia Lack of other pituitary hormones
82
What is the most common cause of Cushing syndrome?
Exogenous - long term corticosteroid therapy
83
What are the first line investigations for Cushing syndrome?
Low dose dexamethsone suppresion test 24hr urinary free cortisol late night salivary cortisol
84
Define acromegaly
Clinical manifestation of excessive growth hormone secretion after the fusion of the epiphysis Leading to large extremities and characteristic faces
85
Define gigantism
The clinical manifestation of excessive growth hormone secretion before the fusion of the long bone epiphysisis Characterised by tall stature Paediatric condition
86
What are the most common causes of acromegaly?
Pituitary adenoma - most common Ectopic GHRH or GH from a tumour
87
How does acromegaly present?
Excessive soft tissue growth - frontal bossing, large ears, large nose, large protruding jaw (prognathism), large tongue If pituitary adenoma cause - bitemporal hemianopia
88
What investigations should be done for acromegaly?
Growth hormone should NOT be done - unreliable fluctuates throughout the day IGF-1 -serum, indicates GH levels GH suppresion test = glucose drink should suppress GH MRI pituitary - pituitary adenoma (note may be too small to see)
89
What are some common complications of acromegaly?
Cardiomyopathy Hypertension Type 2 diabetes Carpal tunnel syndrome Arthiritis Colonic polyps
89
What is the management for acromegaly?
Trans-sphenoid resection of pituitary tumour Radiotherapy may be offered Surgical removal or paraneoplastic tumour (lung or pancreas)
90
What medication may be given to treat acromegaly?
Pegvisomant - GH receptor antagonist Somatostatin analogues - octreotide - block GH release Dopamine agonist - bromocriptine - block GH release

Med 2 (26 decks)

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