Adrenal Gland Pathology Flashcards
What is Addison’s disease?
Hyposecretion of all adrenal steroid hormones due to autoimmune destruction of the adrenal cortex
Name the 3 layers of the adrenal cortex and what they produce
Zona Glomerulosa: Aldosterone
Zona Fasciculata: Cortisol
Zona Reticulum: Androgens
What are the functions of aldosterone?
Decreased K+
Increased Na+ and H2O as water follows salt
Increased blood volume and pressure
What are the causes of Addisons?
Autoimmune adrenalitis
Metastases
Infarction
Infiltration
- Waterhouse-Friderichsen Syndrome
Infection
- TB
- HIV
Iatrogenic
- Adrenalectomy
How does Addisons present?
Depression
Weakness/Fatigue
Hypotension
Amenorrhoea
Salt craving
Weight loss
Abdominal pain
Vitiligo
Unexplained vomiting and diarrhoea: Aldosterone loss
Dizziness: Worse standing, due to aldosterone loss
Areas of darkened skin, lips and gums
Why is hyperpigmentation seen in Addisons?
Low cortisol means no negative feedback and so causes overactive pituitary
This leads to production of pro-opiomelanocortin, a precursor for ACTH
This also leads to production of melanocyte stimulating hormone, as has the same precursor
Resulting in hyperpigmentation
When are symptoms of Addisons seen?
Adrenal cortex has high functional reserve, so when symptoms are present, up to 90% of the cortex has been destroyed
What investigations are used in Addisons diagnosis?
Random Cortisol Test
Short Synacthen Test
- Measures adrenal response to ACTH
Adrenal Autoantibodies
- 21-OHASE
< Na
> K
< Glucose
Describe the Short Synacthen Test?
Measures adrenal response to ACTH
Give ACTH
If cortisol rises, it is an issue at the pituitary, and Addisons
If cortisol stays the same, it is an issue at the adrenal gland
What level of cortisol suggests Addisons?
>550mol/l not Addisons
<500mol/l adrenal status is uncertain
How is Addisons managed?
Glucocorticoid (cortisol)
- Hydrocortisone
Mineralocorticoid (aldosterone)
- Fludrocortisone
What is Addisonian crisis?
Major stressor, such as injury or infection, meaning there is an increased need for cortisol. As body is failing to deliver, symptoms increase
How does Addisonian crisis present?
Loss of consciousness
Hypotension
Severe vomiting and diarrhoea
Sudden pain in back, abdomen or legs
What conditions are associated with Addisons?
Hypothyroidism
Type 1 DM
Premature Ovarian Failure
What is Waterhouse-Friderichsen Syndrome?
Sudden increase in BP causes vessels to rupture, filling adrenal glands with blood and causing ischaemia
What is Phaeochromocytoma?
Tumour of the adrenal medulla, secreting noradrenaline and adrenalin
What % of phaemochromocytomas are benign and unilateral?
90%
What % of phaemochromocytomas are malignant and multiple?
10%
What causes phaemochromocytoma?
Associated with MEN 2A/B
How does phaemochromocytoma present?
Episodic flushing
Palpitations
Sweating
Headache
HTN
Pallor
What investigations are used in phaemochromocytoma?
increased 24 hour urinary collection of metanephrines
MRI adrenal nuclear medicine scan
- Exclude MEN 2
How is phaemochromocytoma managed?
Phenoxybenzamine/Alpha blocker
- Has to be given before B blocker therapy to prevent hypertensive crisis/cardiac arrest during surgery
B Blocker
- HTN control once alpha blocker has had time to work
Laparoscopic adrenalectomy
- Done when patient has stabilised, around 10 days after treatment has started
What is congenital adrenal hyperplasia?
Autosomal recessive condition resulting in partial to complete deficiency of an enzyme necessary for the synthesis of aldosterone or cortisol production in the adrenal gland
What are the causes of congenital adrenal hyperplasia?
21-Hydroxylase Deficiency
11-B-Hydroxylase Deficiency
17a-Hydroxylase Deficiency
What is the most common cause of congenital adrenal hyperplasia?
21-Hydroxylase Deficiency
How does 21-Hydroxylase Deficiency present?
Can present with either salt losing crisis or female virilization
How does 11-B-Hydroxylase Deficiency present?
Presents with female virilization and HTN
How does 17a-Hydroxylase Deficiency present?
Presents with male undervirilization, hypokalaemia and HTN
How is congenital adrenal hyperplasia managed?
Long term replacement with glucocorticoid or aldosterone or both
What is Conn’s syndrome?
Hypersecretion of Aldosterone
How does Conn’s effect K+ and Na+?
>Na absorption
>K excretion
What are the causes of Conns?
Unilateral Adrenocortical adenoma, producing aldosterone
Bilateral adrenal hyperplasia
How does Conn’s present?
Asymptomatic
>HR
- Due to >Na as RAAS is activated
HTN
Hypokalaemia
- Fatigue
- Muscle weakness
- Myalgia
- Muscle cramps
- Hyporeflexia
- Paralysis rarely
What investigations are used in Conn’s diagnosis?
Plasma aldosterone to plasma renin ration
- > Aldosterone (>20)
CT
- Identify tumour
Adrenal Venous Sampling
- Identify which gland is secreting excess hormone
> Na+
< K+
ABG
- Metabolic alkalosis
What is the first line investigation in Conn’s diagnosis and why is this tested?
Plasma aldosterone to plasma renin ration
Shows high aldosterone alongside low renin levels, as negative feedback due to sodium retention
How is Conn’s managed if the cause is adrenal ademona?
Resection
How is Conns managed if the cause is bilateral adrenocortical hyperplasia?
Aldosterone antagonist
Give an example of an aldosterone antagonist
Spironolactone
What organisms cause Waterhouse-Friderichsen Syndrome?
Neisseria Meningitidis
Escherichia coli
Streptococcus Pneumoniae
Haemophilus Influenzae
How does Waterhouse-Friderichsen Syndrome present?
Purpuric rash across body, predominantly on lower limbs and abdomen
Hypoadrenalism symptoms
How is Addison’s management adjusted during intercurrent illness?
Double glucocorticoid and keep the mineralocorticoid dose the same
How is Addisonian crisis managed?
IV 100mg hydrocortisone, continue 6 hourly if patient is stable
Oral replacement may begin after 24 hours and be reduced to maintenance over 3-4 days
1l saline over 30-60mins or with dextrose if hypoglycaemic
Give an example of an alpha blocker
Phenoxybenzamine
What blood abnormality can gluccocorticoid treatment cause?
Neutrophilia
What clinical sign can distinguish between primary adrenal failure and secondary adrenal insufficiency?
Skin hyperpigmentation
How is hydrocortisone dose split throughout the day?
Majority is given the first half of the day
What is the most common cause of Conn syndrome?
Bilateral adrenal hyperplasia
