Cushing's Syndrome Flashcards
What is Cushing’s syndrome?
Cushing’s syndrome occurs because of prolonged exposure to elevated levels of endogenous or exogenous glucocorticoids.
What triggers the secretion of corticotropin-releasing hormone (CRH)?
Stress, time of day, and serum cortisol levels.
What hormone does the pituitary gland secrete in response to CRH?
Adrenocorticotropic hormone (ACTH).
What does the adrenal cortex secrete in response to ACTH?
Cortisol.
What are the functions of cortisol? List at least three.
- Synthesis of glucose (gluconeogenesis)
- Breakdown of proteins
- Inhibits production of inflammatory cytokines
What are the effects of high concentrations of cortisol?
Increased sodium and water retention, increased potassium excretion.
What is the most common exogenous cause of Cushing’s syndrome?
Exogenous glucocorticoids (e.g. prednisolone, hydrocortisone).
What are the two categories of endogenous causes of Cushing’s syndrome?
- Corticotropin-dependent
- Corticotropin-independent
What is the most common type of pituitary adenoma causing Cushing’s syndrome?
Cushing’s disease (80%).
List eight clinical features of Cushing’s syndrome.
- Weakness
- Facial fullness
- Weight gain
- low mood
- reduced libido
- polydipsia, polyuria
- increased infections
What are some clinical findings associated with Cushing’s syndrome?
- Truncal obesity
- Buffalo hump
- Moon facies
- supraclavicular fat pads
- abdominal striae
- proximal muscle wasting
- hypertension
- oedema
What does a 24-hour urinary free cortisol level indicate in Cushing’s syndrome?
Levels >3x normal upper limit.
What is the normal result of a low-dose dexamethasone suppression test?
Morning cortisol suppressed.
What imaging technique is used to confirm the presence of a pituitary adenoma?
MRI pituitary.
What is the first step in managing exogenous Cushing’s syndrome?
Review glucocorticoid treatments and reduce doses.
