Which part of the adrenal gland is responsible for producing mineralocorticoids?
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?
The medulla of the adrenal gland is responsible for secreting what?
What is the zona reticularis responsible for secreting?
How are cortisol and androgen production regulated?
Hormones from the hypothalamus and anterior pituitary
Describe the steps which lead to cortisol production
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?
- Angiotensin II causes vasoconstriction
- Aldosterone causes salt (and water) retention
What are the 6 classes of steroid receptors?
- Vitamin D
The following signs and symptoms are characteristic of what?
- Darkened skin
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
- 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?
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
How is the skin affected in Cushing's syndrome?
- Buffalo hump
- Thin skin/easy bruising
- Increased abdominal fat
What are the most common causes of ACTH dependent Cushing's syndrome?
- Pituitary adenoma*
- Ectopic ACTH (tumour)
- Ectopic CRH
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?
(due to adrenal adenoma)