Hypoadrenalism Flashcards
Where are the adrenal glands?
On top of kidneys
The adrenal glands have two sections, name them?
Medulla
Cortex
What does the medulla secrete and when does it secrete?
Adrenaline
Noradrenaline
In response to sympathetic stimulation
What does the cortex secrete?
Corticosteroids:
- mineralcorticoids
- glucocorticoids
- androgens
What are the corticosteroids made of?
Cholesterol
Give some examples of:
- mineralcorticoids
- glucocorticoids
- androgens?
Mineralcorticoids: aldosterone
Glucocorticoids: cortisol
Androgens: sex hormones, testosterone
Name the 3 regions of the cortex of each adrenal glands going from outside - in?
Zona glomerulosa
Zona fasciculata
Zona reticularis
Describe/draw axis of cortisol?
Hypothalamus releases CRH (corticotrophic releasing hormone)
This acts on pituitary making it release ACTH (adrenocorticotrophic hormone)
This acts on adrenals making them produce cortisol
What does cortisol do?
Helps body overcome stress Decreased immune function Maintain BP Metabolism of fats, proteins Circadian rhythms
Describe how cortisol is involved in control of circadian rhythms?
Light falls on retina
Transmission of impulses from eye to the central clock, in the hypothalamus
This then triggers the release of cortisol which wakes the body up
What is the name for primary hypoadrenalism?
Addison’s disease
What is Addison’s disease?
Autoimmune destruction of the adrenal cortex
Reduction in ability to produce cortisol, aldosterone and androgens
Clinical features of Addison’s disease?
Insidious onset
Lethargy, fatigue Depression Anorexia Weight loss Weakness
Postural hypotension
Hyperpigmentation
Loss of body hair in women
Vitiligo: loss of pigment of skin
Where does hyperpigmentation occur in Addison’s disease? And why?
Seen in buccal mucosa (mouth)
Pressure points
Skin creases
Recent scars
Caused by excess ACTH which stimulates melanocytes to make the skin darker
Why are there higher levels of ACTH in Addison’s disease patients?
Because the pituitary gland senses no cortisol/aldosterone/androgens coming from adrenals
It tries to stimulate the adrenals to make more
What causes Addison’s disease to develop?
Organ specific antibodies
There are links with other autoimmune diseases
Adrenal gland TB
Surgical removal
Investigation of Addison’s disease?
Hyponatraemia
Hyperkalaemia
Hypoglycaemia
Random cortisol levels low
ACTH stimulation test (SynACTHen test)
What is the ACTH stimulation test?
Synacthen test
Patient is given synthetic ACTH to stimulate cortisol production
Cortisol levels should rise sharply, but they don’t in Addison’s disease
Why does Addison’s disease cause hyponatraemia and hyperkalaemia?
Low aldosterone levels means less sodium is retained in the tubules and less potassium is secreted
Treatment of Addison’s disease?
Replacement!
Hydrocortisone: replacement cortisol
Fludrocortisone: replacement aldosterone
What happens if you over-replace cortisol in Addison’s disease?
You get endogenous Cushing’s syndrome
In healthy people, when do cortisol levels rise?
3rd trimester of pregnancy
During stressful time like trauma, surgery, illness
What is an adrenal crisis?
Also known as Addisonian crisis
When an event such as trauma or illness, causes severe hypotension and dehydration
Clinical features of an adrenal crisis?
Vomiting Abdominal pain Profound weakness Hypoglycaemia Hypovolaemic shock