17. Steroids Flashcards
What is cortisol?
This is a steroid hormone - of the glucocorticoid class of hormones
Where and when is cortisol produced in the body?
Produced by the zona fasciculata of the adrenal gland
Released in response to stress and low blood glucose concentration
Describe the levels of cortisol in the body
Cortisol levels are the highest in the morning upon waking and are the lowest in the evening
The cortisol levels rise significantly in stress induced situations
How can cortisol be give n as a form of medication?
Can be given as ‘cortizone’ and this is metabolised by the body to cortisol
What is the role of cortisol in the body?
Metabolic effect e.g. stimulation of gluconeogenesis, anti-inflammatory pathways, glycogenosis
Immune response - prevents the release of substances that can cause over inflammation - acts to dampen down the immune system where it may cause unnecessary damage
What are the side effects of long term treatment of cortisol?
Oedema Weight gain Glaucoma Hypertension Insomnia Depression Thrombosis GI bleeding Peptic ulcers Pancreatitis Osteoporosis
What is Cushing’s syndrome?
A collection of signs and symptoms due to prolonged exposure to cortisol
Can be due to medication or excess production by a tumour - if it is due to express production via an pituitary adenoma then it is known as Cushing’s disease
What are corticosteriods?
These are a class of steroid hormones that are produced by the adrenal cortex There are two main types - glucocorticoids and mineralocorticoids
NB. THE TERMS CORTICOSTEROIDS AND GLUCOCORTICOIDS ARE OFTEN USED AS SYNNONYMS
What is the effect of corticosteroids on the bone?
Corticosteroids have an effect on both osteoclasts (break down bone) and on osteoblasts (build up bone)
Inhibits osteoblasts AND inhibits osteoclasts but to a lesser extent SO the net effect is osteoporosis
Why do corticosteroids have such wide ranging effects?
Because the human glucocorticoid receptor is found in almost every tissue and cell type in the body - even those without a nucleus e.g. erythrocytes and platelets
Describe the types of glucocorticoid receptors and why these exist
There are two forms of the glucocorticoid receptor - alpha form and a beta form
The alpha form binds steroids but the beta form does not bind steroids
This is so that the tissue can regulate the action of the corticosteroids depending on how much of the alpha/beta form is produced relative to each other
What are the different types of these glucocorticoid receptors and how do they work?
Can work in two ways:
1) Genomic - slow effect - on the actual DNA - activates transcription and effects the genome (nuclear receptors)
2) Non-genomic - rapid effect - not on the actual DNA or genome but on other receptors (membrane or cytoplasmic receptors)
Why is it dangerous to suddenly stop the treatment of someone on long term steroid medication?
Because when you are on treatment, the patient then stops producing steroids due to the feedback loop
SO you need to gradually reduce the dosage rather than suddenly stop it
