Cushings Flashcards
What is Cushing’s syndrome?
Prolonged levels of glucocorticoids (cortisol)
What are the 2 groups of corticosteroid hormones? Give an example of each
• Glucocorticoids (e.g., cortisol)
• Mineralocorticoids (e.g., aldosterone)
Where specifically is cortisol produced?
Zona fasciculata
Where are mineralocorticoids produced?
Zona glomerulosa
What is produced from the Zona glomerulosa?
Mineralocorticoids such as aldosterone
What is produced from the Zona fasciculata?
Corticosteroids e.g. cortisol
And a small amount of androgens
What is produced from the zona reticularis?
produces and secretes androgens such as dehydroepiandrosterone (DHES). It also secretes a small amount of corticosteroids.
What is released from the medulla? What is the name of the cells they are released from?
Catecholamines e.g. adrenaline
Chromaffin cells
What are some symptoms of Cushing’s? (8)
o Weakness
o Facial fullness
o Weight gain
o Low mood
o Decreased libido
o polydipsia
o polyuria
o Increased frequency of infection
Which sign of Cushing’s is specific to Cushing’s disease?
o Hyperpigmentation of the skin in patients with Cushing’s disease (due to high ACTH levels)
What are some signs of Cushing’s? (12)
o Round face (known as a “moon face”)
o Central (truncal) obesity
o Abdominal striae (stretch marks)
o Enlarged fat pad on the upper back - dorsal fat pad
o Proximal limb muscle wasting (with difficulty standing from a sitting position without using their arms) - proximal myopathy
o Male pattern facial hair in women (hirsutism)
o Easy bruising and poor skin healing
o Hyperpigmentation of the skin in patients with Cushing’s disease (due to high ACTH levels)
○ ACTH is stimulating melanocytes to produce melanin
○ This is absent if the cause is an adrenal adenoma or exogenous steroids
o Hypertension
o Signs of tumour in Cushing’s disease e.g. headaches, visual field defects
o Acne
What type of ABG is seen in Cushing’s?
Hypokalaemic metabolic alkalosis
What are some complications of Cushing’s? (5)
• hypertension
• diabetes
• obesity
• Metabolic syndrome
• Osteoporosis
What is Nelson’s syndrome?
• Nelson’s syndrome = development of an ACTH-producing pituitary tumour after the surgical removal of both adrenal glands due to a lack of cortisol and negative feedback. It causes skin pigmentation (high ACTH), bitemporal hemianopia and a lack of other pituitary hormones.
Which drugs can be used to treat Cushing’s before surgery? (3)
Metyrapone, ketoconazole + mitotane
What are the causes of Cushing’s? (4)
o C – Cushing’s disease (a pituitary adenoma releasing excessive ACTH)
o A – Adrenal adenoma (an adrenal tumour secreting excess cortisol)
o P – Paraneoplastic syndrome – ACTH is released from a tumour somewhere other than the pituitary gland (ectopic ACTH) stimulating excessive cortisol release from the adrenal gland e.g. small cell lung cancer
o E – Exogenous steroids (patients taking long-term corticosteroids)
What is the cause of Cushing’s disease?
Pituitary adenoma secreting acth
What is the main investigation in Cushing’s?
Dexamethasone suppression tests
What is the bodies normal response in the dexamethasone suppression test?
Suppressed cortisol due to negative feedback
What is seen in Cushing’s in a low dose overnight test?
Failure to suppress morning cortisol
What is seen in Cushing’s in a low dose 48 hour test?
Failure of cortisol suppression on day 3
Which cause of Cushing’s has suppression of cortisol in a high dose 48hr test?
Pituitary adenoma
Which 2 causes of Cushing’s have high acth?
Pituitary adenoma
Ectopic acth e.g. small cell lung cancer
In which cause of Cushing’s is acth low? (2)
• ACTH is suppressed due to negative feedback on the pituitary when excess cortisol comes from an adrenal tumour (or endogenous steroids)
What level of 24hour urinary free cortisol is suggestive of Cushing’s?
3 x upper limit of normal
What is the normal variation of cortisol release?
Diurnal
Decreases in evening compared to morning
What happens to the late night salivary cortisol measurement in Cushing’s?
Cortisol is not suppressed in evenings
