Adrenal disorders Flashcards
What can abnormal amounts of messengers cause
Abnormal amounts of messenger cause cells to misbehave all over the body: syndromes of excess and deficiency
Adrenal failure = Addison’s
Excess cortisol = Cushing’s
Describe the anatomy of the adrenal gland
Left adrenal vein drains into renal vein
Right adrenal vein drains into IVC
Both adrenals have many arteries but only one vein
So the left indirectly feeds and the right directly feeds.
Describe the passage of the arteries in the adrenal glands
The arteries pass through the cortex and pick up all the hormones that the adrenal gland makes. This is then delivered to the central vein.
What is the risk associated with a left adrenalectomy
Spleen at risk with left adrenalectomy
therefore immunise with HIB (haemophilus influenzae (B)) and pneumovax before elective left adrenalectomy
(HIB and pneumovax are common in people who have lost their spleen).
What is pneumovax
pneumococcal vaccination against several strains of Step. Pneumococcus
Describe the different layers of the adrenal gland
o Glomerulosa – Aldosterone. o Fasciculata – Cortisol. o Reticularis – Androgens (but doesn’t really do much as it’s a remnant from evolution). o Medulla – Catecholamines (e.g. adrenaline).
What is the precursor of the adrenal gland secretions
Cholesterol
What is meant by a hormone
Blood borne (circulating) messenger
Describe the different types of hormone
Peptides (prolactin, GH, ACTH)
steroids (testosterone, cortisol)
amines (adrenaline, thyroxine.)
Are all steroid hormones derived from cholesterol
No, they can be derived from other raw materials too.
Draw cholesterol
See diagram
Describe how different products are produced from cholesterol
Protein that catalyses a specific reaction
various enzymes present in cells
specific enzymes catalyse the synthesis of particular alterations to the molecule- different enzymes in different layers of adrenal gland alter cholesterol differently, giving rise to different products.
What is the production of cortisol controlled by
ACTH
Why are the adrenal glands not as important in the production of sex hormones
The gonads have evolved to do this
What does cortisol have a negative feedback effect on
The production of ACTH
Direct on pituitary
Indirect on hypothalamus
In the synthesis of the adrenal hormones from cholesterol, what is the base of all the enzymes
P450c
What is the role of P450c21
Converts progesterone into 11 deoxycorticosterone
Converts 17 OH progesterone into 11 deoxycortisol
What is the role of p450c17
Converts progesterone into 17 OH progesterone
What is the role of P450c11
Converts 11 deoxycorticosterone into corticosterone
Converts 11 deoxy cortisol into cortisol
What is the role of P450c18
Converts corticosterone into aldosterone
Draw HPA axis
See diagram
Describe the production of cortisol
Cortisol control by ACTH: ▪ Cortisol is needed when under stress (e.g. physical or trauma) and ACTH turns on the correct ENZYMES needed to make cortisol. ▪ On the other hand, if you needed aldosterone, you can turn on the enzymes using the reninangiotensin system. ▪ I.E. If you turn on different enzymes, you make different hormones.
Binding of hormone receptor turns on that enzyme pathway
Describe POMC
POMC = pro-opio-melanocortin
POMC is a large precursor protein that is cleaved to form a number of smaller peptides, including ACTH, MSH (Melanocyte stimulating hormone) and endorphins
Thus people who have pathologically high levels of ACTH may become tanned
Where does the tan appear
Everywhere, even in the mouth
Describe Addison’s disease
Primary adrenal failure
autoimmune disease where the immune system decides to wipe out the adrenal cortex (UK)
tuberculosis of the adrenal glands (commonest cause worldwide)
What is an indication of Addison’s disease
High levels of ACTH.
Describe some of the symptoms of Addison’s disease
o Skin pigmentation (inappropriate). o Freckling. o GI disturbances. o Postural Hypotension (standing up) – lack of cortisol and aldosterone to manage. o Hypoglycaemia. o Weight loss. o Autoimmune vitiligo.
What is autoimmune vitiligo
Autoimmune disease of the skin; autoimmune candidates often come together.
What are the treatments for Addison’s disease
Rehydrate with normal saline
Give dextrose to prevent hypoglycaemia which could be due to the glucocorticoid deficiency
give hydrocortisone or another glucocorticoid
Summarise the key features of Addison’s
Summary includes: Cortisol deficiency, salt loss, hypotension, eventual death if untreated.
What does a low Na+ conc as a result of Addison’s cause
Low blood pressure and hence weakness
What is the disease caused by excess cortisol production called
Cushing’s syndrome
Describe the biological actions of excess cortisol
Impaired glucose tolerance (diabetes) weight gain (increase fat, lose protein)
thin skin and easy bruising
striae (stretch marks)
proximal myopathy (muscle weakness)
mental changes (depression)
Hypertension
fat redistribution
moon face
buffalo hump (interscapular fat pad)
Can Cushing’s syndrome be caused by an excess of any other glucocorticoid
The main reason for Cushing’s syndrome is an excess of cortisol but it can be ANY OTHER glucocorticoid
Describe the symptoms of Cushing’s syndrome
Impaired glucose tolerance (diabetes) weight gain hirsutism (facial hair) and acne thin skin and easy bruising striae (stretch marks) proximal myopathy (muscle weakness) mental changes (depression)
What are the 4 causes of Cushing’s syndrome
Taking steroids by mouth (common)
pituitary dependent Cushing’s disease (pituitary adenoma)
Ectopic ACTH (lung cancer)
adrenal adenoma or carcinoma
What is meant by ectopic ACTH
Some lung cancer cells start to produce ACTH (removal of cells removes the symptoms of Cushing’s syndrome)
Describe pituitary adenoma
adenohypophysis produces too much ACTH.
What is the difference between Cushing’s syndrome and Cushing’s disease
Cushing’s DISEASE is associated ONLY with a pituitary adenoma; every other cause gives rise to Cushing’s SYNDROME.
What are the side effects of steroids
Hypertension
Diabetes
Osteoporosis
reactivation of infection (immunosuppression)
easy bruising
poor wound healing, thin skin
The side effects of ‘steroids’ is more or less the same as the symptoms of Cushing’s Syndrome.
Why do patients with Cushing’s syndrome present with thin skin
Cortisol drives the body to make fat, but no protein, hence the skin becomes thinner.
Describe aldosterone producing adenoma
Conn’s syndrome
Hypertension (difficult to treat)
oedema
low potassium
