L28: Endocrine Disorders

Question 1

Which hormone disorders can be a result of the gland itself?

Answer 1

→Graves disease

→Hashimoto

Question 2

What disorders can be a result of adrenal hyperfunction?

Answer 2

→Excess cortisol (Cushing’s syndrome)

→Excess aldosterone (e.g. Conn’s syndrome)

→Adrenal insufficiency
Hypocortisolism
Lack of aldosterone and cortisol (Addison’s)

Question 3

What is Conn’s syndrome?

Answer 3

→Aldosterone excess
primary hyperaldosteronism

→adrenal gland itself producing excess

Question 4

What is Cushing’s syndrome?

Answer 4

→Cortisol excess

Question 5

What is aldosterone secretion activated by?

Answer 5

→RAAS

→Increased plasma [K+]

Question 6

What is RAAS activated by?

Answer 6

→Reduced renal perfusion

→Increased sympathetic activity

→Interpreted as fall in blood volume

Question 7

What is useful in diagnosing primary hyperaldosteronism?

Answer 7

→plasma aldosterone/renin ratio

Question 8

What are some roles of cortisol?

Answer 8

→Preserves plasma glucose

→promotes insulin resistance in muscles

→Promotes lipolysis, gluconeogenesis

Question 9

What are some effects of excess cortisol?

Answer 9

→hyperglycemia,

→increased adiposity,
→hypertension,
→muscle wasting

Question 10

What rises in absence of cortisol?

Answer 10

→ADH

Question 11

What are the most common causes of Cushing’s syndrome?

Answer 11

→Exogenous glucocorticoids activate cortisol receptor

→Adrenal cortex atrophies with lack of ACTH stimulation

→Several days may be required for adrenal to become responsive to ACTH again

Question 12

How is Cushing’s disease diagnosed?

Answer 12

→dexamethasone test

Question 13

What is the dexamethasone test?

Answer 13

→After a dose of dexamethasone, cortisol levels often stay very high in people who have Cushing’s syndrome

Question 14

In adrenal tumour what will the plasma ACTH be after dexamethasone test?

Answer 14

→low

Question 15

In ectopic ACTH what would the level of ACTH be after dexamethsasone?

Answer 15

→very high

Question 16

What is primary adrenal insufficiency?

Answer 16

→Addison’s disease- destruction of adrenal cortex

→Insufficient cortisol and aldosterone

Question 17

What is secondary adrenal insufficiency?

Answer 17

→Pituitary or hypothalamic disease

→Insufficient cortisol

Question 18

What is the primary stimulator for ADH?

Answer 18

→osmolarity

Question 19

What are the clinical features of Addison’s?

Answer 19

→Hypotension 
→Plasma [Na+]: normal to low
→Hyponatremia- increased ADH
→Plasma [K+]: normal to high
→High ACTH
→Elevated plasma renin

Question 20

Why is there hyperpigmentation in Addison’s?

Answer 20

→ACTH reacts with melanocytes receptors

Question 21

What are the hallmarks of Addison’s?

Answer 21

→high ACTH

→low cortisol

Question 22

What is used for ACTH testing?

Answer 22

→Synacthen

→Assess ability of adrenal to produce cortisol in response to ACTH

Question 23

What is involved in the short Synacthen test?

Answer 23

→Measure baseline cortisol (9am) and 30 min after 250 µg synacthen (synthetic ACTH) i.m.

→Adrenal insufficiency is excluded by an increase in cortisol of >200 nmol/L and/or a 30 min value >550

Question 24

What is involved in the Synacthen long test?

Answer 24

→Adrenal cortex ‘shuts down’ in absence of stimulation by ACTH – time needed to regain responsiveness

→3-day stimulation with synacthen

→In secondary (but not primary) adrenal insufficiency cortisol increases by >200 nmol/L over baseline

→Long test not often necessary since ACTH assay can distinguish