Lecture 11: Clinical Aspects of the Adrenal Gland Clinical Case & Discussion Flashcards
what other autoimmune disease are associated with Addison’s disease?
- thyroid disease (20%)
- type 1 diabetes mellitus (15%)
- premature ovarian failure (15%)
what are common symptoms associated with primary adrenal failure?
- weakness, fatigue, anorexia, weight loss
- skin pigmentation or vitiligo
- hypotension
- unexplained vomiting or diarrhoea
- salt craving
- postural symptoms
diagnosis of adrenal insufficiency involved which investigations?
- routine bloods: U&E, glucose, FBC
- random cortisol: > 450nmol/l (not Addison’s), < 450nmol/l (adrenal status uncertain)
- synacthen test (and basal ACTH)
- if suspicion high and patient is unwell, treat with steroids and do synacthen test later
in the case of secondary adrenocortical insufficiency, is plasma ACTH suppressed or elevated?
suppressed
in the case of primary adrenocortical insufficiency, is plasma ACTH suppressed or elevated?
elevated
list the glucocorticoid replacement drugs used in adrenal insufficiency
- hydrocortisone 20-30mg
- prednisolone 2.5mg
- dexamethasone 0.75mg
- given in divided doses to mimic normal diurnal variation
describe mineralocorticoid replacement therapy used for adrenal insufficiency
- synthetic steroid, fludrocortisone
- binds to mineralocorticoid receptors
- 50-300 mg daily
- adjust dose according to clinical status, U&E, plasma renin level
what are the three important ‘self-care’ rules for patients on steroids?
- never miss steroid doses
- double the hydrocortisone dose in event of intercurrent illness (e.g. flu, UTI)
- if severe vomiting or diarrhoea, call for help without delay
what % of Cushing’s syndrome is caused by a pituitary tumour (Cushing’s disease)?
ACTH-dependent
75%
what % of Cushing’s syndrome is caused by ectopic ACTH secretion (e.g. lung carcinoid)?
ACTH dependent
5%
what % of Cushing’s syndrome is caused by an adrenal tumour (adenoma or carcinoma)?
ACTH-independent
20%
list the screening tests for Cushing’s syndrome
- 24hr urinary free cortisol (normal 14-135nmol/24h)
- 1mg overnight dexamethasone suppression test taken
treatment for Cushing’s disease
Surgery is treatment of choice to remove causative tumour.
Medical:
- adrenal hormone synthesis inhibitors: ketoconazole, metyrapone, aminoglutethimide, etomidate
- destroy adrenocortical cells: mitotane
- radiotherapy
- bilateral adrenalectomy
what does a PAC/PRA ratio > 20 indicate?
PAC = primary aldosterone concentration PRA= plasma renin activity
primary hyperaldosteronism e.g. Conn’s syndrome caused by an adrenal adenoma or bilateral hyperplasia)
- elevated plasma aldosterone concentration
- suppressed plasma renin activity
what does an elevated PRA and PAC indicate? (PAC/PRA ratio <20)
PRA= plasma renin activ
- secondary hyperaldosteronism
- essential hypertension
what screening tests are performed when there is clinical suspicion of hyperaldosteronism?
- plasma renin activity (PRA)
- plasma aldosterone concentration (PAC)
- PAC/PRA > 20 with concomitant serum aldosterone > 10ng/dl
which confirmatory test is performed when there is clinical suspicion of hyperaldosteronism after positive screening tests?
24-hr urine aldosterone > 12 ug/day and urinary sodium > 200 mEq/day during 4 days of salt loading
give an example of a hypersecretion disorder affecting the adrenal medulla?
- phaeochromocytoma (excess catecholamines e.g. epinephrine)
clinical features of phaeochromocytoma
- hypertension (persistent in 70%)
- paroxysmal attacks: headache, sweating, palpitations, tremor, pallor, anxiety/fear
what causes congenital adrenal hyperplasia?
- > 90% cases due to 21-hydroxylase deficiency (cannot produce cortisol, aldosterone)
features of congenital adrenal hyperplasia
Severe cases:
- neonatal salt-losing crisis
- ambiguous genitalia (girls)
Incomplete defects:
- pseudo-precocious puberty (boys)
- hirsutism (women)
