Adrenal Disorders Flashcards
Which part of the adrenal gland is responsible for producing mineralocorticoids?
Zona glomerulosa
What are the three components of the adrenal cortex?
- Zona glomerulosa
- Zona fasiculata
- Zona reticularis
What regulates the zona glomerulosa?
- K+ concentration
- Angiotensin II (RAAS)
Which part of the adrenal gland produced glucocorticoids and in response to what?
Zona fasiculata
ACTH
The medulla of the adrenal gland is responsible for secreting what?
Catecholamines
What is the zona reticularis responsible for secreting?
Androgens
How are cortisol and androgen production regulated?
Hormones from the hypothalamus and anterior pituitary
Describe the steps which lead to cortisol production
Hypothalmic-pituitary-adrenal axis
Hypothalamus releases corticotropin releasing hormone
Anterior pituitary releases adrenocorticotropin hormone (ACTH)
Adrenal cortex releases cortisol
When is the RAAS pathway activated?
Low blood pressure
What is the result of an activated RAAS pathway?
Increased BP
- Angiotensin II causes vasoconstriction
- Aldosterone causes salt (and water) retention
What are the 6 classes of steroid receptors?
- Androgen
- Glucocorticoid
- Mineralocorticoid
- Oestrogen
- Progestin
- Vitamin D
The following signs and symptoms are characteristic of what?
- Darkened skin
- Dehydration
- Hypotensive
- Hyponatraemia
Primary adrenal insufficiency
What are the three main causes for primary adrenal insufficiency?
- Addison’s disease
- Congenital adrenal hyperplasia
- Adrenal Tb or malignancy
Secondary adreanl insufficiency may be due to which 3 main causes?
- Lack of ACTH stimulation
- Iatrogenic (excess exogenous steroid)
- Pituitary/hypothalmic disorders
Addison’s disease is associated with other _________ conditions and in most cases auto_________
Addison’s disease is associated with other autoimmune conditions and in most cases autoantibodies
What are the key clinical features of Addison’s disease?
- Anorexia and weight loss
- Fatigue
- Dizziness and low BP
- Abdominal pain, nausea and vomiting
- Skin pigmentation
Why is Addison’s disease associated with skin pigmentation?
Build up of ACTH
How can adrenal insufficiency be diagnosed?
Synacthen test
Measure plasma cortisol before and 30 minutes after IV/IM ACTH injection
Normal = >250nmol/L (before), >550nmol/L (after)
Adrenal insufficiency is associated with _____glycaemia
Adrenal insufficiency is associated with hypoglycaemia
How is adreanl insufficiency treated?
- Hydocortisone (cortisol replacement)
- Fludrocortisone (aldosterone replacement)
The clinical features of secondary adrenal insufficiency are similar, except for which two things?
- Pale skin (there is not excess ACTH)
- Aldosterone production is intact
What are the facial features of someone with Cushing’s syndrome?
- Moon face
- Plethoric (flushed) cheeks/acne
- Cataracts
How is the skin affected in Cushing’s syndrome?
- Buffalo hump
- Thin skin/easy bruising
- Increased abdominal fat
- Striae
What are the most common causes of ACTH dependent Cushing’s syndrome?
- Pituitary adenoma*
- Ectopic ACTH (tumour)
- Ectopic CRH
*Cushing’s disease
What are the causes of ACTH independent Cushing’s?
- Exogenous steroids
- Adrenal adenoma
- Adremal carcinoma
- Nodular hyperplasia
Which tests can be done to establish a cortisol excess in suspected Cushing’s?
- Overnight dexamethasone suppression test
- 24 hour urinary free cortisol
- Late night salivary cortisol
Which test is generally done to diagnose Cushing’s?
Low dose dexamethasone suppression test
What is the commonest cause of cortisol excess?
Iatrogenic (exogenous steroids)
What is the downside to chronic exogenous steroid use?
Chronic suppression of pituitary ACTH
Adrenal atrophy will occur
What is Conn’s syndrome?
Primary aldosteronism
(due to adrenal adenoma)
How does primary aldosteronism come about?
Autonomous aldosterone production
(independent of angiotensin II/ K+ conc)
What are the actions of aldosterone in the body?
- Increases sympathetic outflow
- Sodium retention
- Cytokine and ROS synthesis
- Increased cardiac collagen synthesis
- Endothelial dysfunction
What is the most common secondary cause of hypertension?
Primary aldosteronism
What are the key clinical features of primary aldosteronism?
- Hypertension
- Hypokalaemia
- Alkalosis
What are the two main subtypes of primary aldosteronism?
- Adrenal adenoma (Conn’s)
- Bilateral adrenal hyperplasia
How is primary aldosteronism diagnosed?
- Measure plasma aldosterone to renin ratio
- If ratio is raised, attempt saline suppression test
- Failure of plasma aldosterone to suppress by >50% with 2L of normal saline confirms PA
How can the subtype of primary aldosteronism be confirmed?
Adrenal CT (demonstrates adenoma)
PET scan (demostrates adenoma/bilateral hyperplasia)
What are the treatment options for primary aldosteronism
a) Caused by adenoma
b) Caused by bilateral adrenal hyperplasia?
a) Unilateral laparoscopic surgery
b) MR antagonists e.g. spironolactone
