Endocrinology: Pathology - Adrenal cortex and medulla Flashcards
List six causes of Cushing syndrome. Which of these are ACTH-dependent and which are ACTH-independent? Which is most common?
- Exogenous glucocorticoids (most common)
ACTH-dependent:
2. ACTH-secreting pituitary adenomas (most common ACTH-dependent, 70%; “Cushing disease”)
3. Corticotroph cell hyperplasia (primary or secondary due to hypothalamic dysfunction with raised CRH)
4. Ectopic ACTH secretion by non-pituitary tumours
ACTH-independent:
5. Primary adrenal neoplasm
6. Primary cortical hyperplasia (rare)
What is the most common non-pituitary tumour to secrete ACTH?
Small cell lung Ca
Which primary adrenal neoplasm causes more marked hypercortisolism?
Carcinoma
What are the four morphological patterns seen in the adrenal gland in the setting of hypercortisolism, and what causes each?
- Focal atrophy: due to exogenous glucocorticoids
- Diffuse hyperplasia: due to ACTH-dependent causes
- Micronodular and macronodular hyperplasia: primary hyperplasia
- Pituitary adenoma or carcinoma
What derangements in serum ACTH and response to dexamethasone suppression test are seen in the setting of pituitary causes of Cushing syndrome vs ectopic ACTH syndromes vs adrenal tumours?
Pituitary causes:
- Increased ACTH
- No change in ACTH or urinary cortisol excretion with low doses
- Reduced ACTH and suppression of urinary cortisol excretion with higher doses
Ectopic ACTH:
- Increased ACTH
- No change in ACTH or urinary cortisol excretion with low or high doses
Adrenal tumours:
- Decreased ACTH (due to negative feedback)
- No change in ACTH or urinary cortisol excretion with low or high doses
List three causes of primary hyperaldosteronism. Which of these is most common?
- Bilateral idiopathic hyperaldosteronism (most common, 60%)
- Adrenocortical neoplasm (aldosterone-producing adenoma, adrenocortical carcinoma)
- Primary familial hyperaldosteronism (including glucocorticoid-suppressible)
What is Conn syndrome?
Hyperaldosteronism caused by aldosterone-secreting adenoma
Describe three broad causes of secondary hyperaldosteronism with specific examples of each
- Decreased renal perfusion (e.g. renal artery stenosis, arteriolar nephrosclerosis)
- Arterial hypovolaemia and oedema (e.g. CCF, cirrhosis, nephrotic syndrome)
- Pregnancy
What is the pathogenesis of pregnancy-induced hyperaldosteronism?
Due to oestrogen-induced increase in plasma renin
What is the difference in plasma renin activity between primary and secondary causes of hyperaldosteronism?
Primary: decreased plasma renin activity with increased aldosterone:renin activity ratio (must be confirmed with aldosterone suppression test)
Secondary: increased plasma renin activity
Describe the clinical presentation of primary and secondary hyperaldosteronism
Both present with HTN, and Na+ and fluid retention
Primary hyperaldosteronism may also present with hypokalaemia
Describe two broad causes of primary adrenocortical insufficiency with specific examples of each
- Loss of cortex (e.g. congenital hypoplasia, AI adrenalitis, infection, systemic AI conditions such as sarcoidosis and amyloidosis, metastatic carcinoma)
- Failure of metabolism (e.g. congenital hyperplasia, drug- or steroid-induced ACTH inhibition)
Describe two broad causes of secondary adrenocortical insufficiency with specific examples of each
- Hypothalamic-pituitary disease (e.g. neoplasm, infection, infiltrative disease such as sarcoidosis, inflammation)
- Hypothalamic-pituitary suppression (e.g. long-term steroid administration, steroid-producing neoplasms)
What are the three syndromes that adrenocortical insufficiency may present as?
- Primary acute adrenocortical insufficiency
- Primary chronic (Addison disease) adrenocortical insufficiency
- Secondary adrenocortical insufficiency
Give three causes of primary ACUTE adrenocortical insufficiency
- Acute stress (e.g. surgery, infection) in setting of chronic adrenocortical insufficiency
- Rapid withdrawal of exogenous steroids after prolonged treatment
- Massive adrenal haemorrhage (e.g. in newborns, Waterhouse-Friderichsen syndrome)
What is Waterhouse-Friderichsen syndrome? Who does it most commonly affect?
Acute adrenal failure due to adrenal haemorrhage secondary to severe bacterial infection
More common in children