Adrenals Flashcards
what is adrenal insufficiency
Inadequate adrenocortical function- not producing cortisol or aldosterone
what is included in Primary adrenal insufficiency
Addison’s disease
Congenital Adrenal Hyperplasia (CAH)
Adrenal TB/malignancy
what is congenital adrenal hyperplasia (CAH)
genetic condition where there is deficiency of cortisol and aldosterone production, pretty rare
what is the cause of Congenital adrenal hyperplasia and what does it result in
Autosomal recessive
Lack of 21-hydroxylase activity
Deficiency of cortisol and aldosterone
Increased adrenal androgens
what is Addison’s Disease
Autoimmune destruction of adrenal cortex = decreased cortisol production
>90% destroyed before symptomatic
what other auto immune conditions is Addisons diseases associated with
Type 1 DM,
autoimmune thyroid disease,
pernicious anaemia,
coeliac disease
People with addisons disease, up to 60% have other autoimmune disease
what are the clinical features of addisons disease
Anorexia, weight loss Fatigue/lethargy Dizziness and low BP Abdominal pain, vomiting, diarrhoea Skin pigmentation- (commonly in buccal mucosa and in palmar creases)
how to diagnose adrenal insufficiency
1) ‘Suspicious biochemistry’
high Na, low K
Hypoglycaemia- very difficult to develop if not diabetic and on insulin medication
2) SHORT SYNACTHEN TEST
Measure plasma cortisol before and 30 minutes after iv ACTH injection
Normal: baseline >250nmol/L, post ACTH >480
3) Measuring ACTH levels
Should be high (causes skin pigmentation)
4) Renin/Aldosterone level
Increased renin, low aldosterone
5) Adrenal autoantibodies
what is the management of adrenal insufficiency
Hydrocortisone (synthetic equivalent) as cortisol replacement
- If unwell, give intravenously first
- Then 15-30mg tablets daily in divided doses
- Try to mimic diurnal rhythm
Fludrocortisone (synthetic equivalent) as aldosterone replacement
Careful monitoring of BP and plasma potassium
What is included in secondary adrenal insufficiency
–> Due to lack of ACTH production by pituitary gland
Pituitary/hypothalamic disease Tumours
- Surgery/radiotherapy
Exogenous steroid use- Commonest cause
give examples of exogenous steroids that cause secondary adrenal insufficiceny
High dose prednisolone
Dexamethasone
Inhaled corticosteroid
what are the clinical features and management of secondary adrenal insufficiency
Clinical features: Anorexia, weight loss Fatigue/lethargy Dizziness and low BP Abdominal pain, vomiting, diarrhoea NO SKIN PIGMENTATION (no increased ACTH)
Management:
Hydrocortisone Treatment
what is Cushing’s syndrome:
Excess cortisol secretion
what are the clinical features of cushing’s syndrome
Easy bruising Facial plethora Striae- stretch mark Proximal myopathy- Increased abdominal fat Thin arm and legs Moon face Buffalo hump
what are the causes of Cushings syndrome (ACTH dependent and independent)
ACTH dependent (excess ACTH = excess cortisol)
- Pituitary adenoma (68%) Cushing’s Disease
- Ectopic ACTH 12% (carcinoid/carcinoma)- lung cancer, broncho carcinoid
- Ectopic CRH <1%
ACTH independent (adrenal problem- autonomous production of cortisol)
Adrenal adenoma
Adrenal carcinoma
Nodular hyperplasia
how to diagnose Cushing’s syndrome
1) Establish cortisol excess
- Dexamethasone suppression testing
Normally, person switches off cortisol production next day but this doesn’t occur in people with cushings’ syndrome
- 24 hour urinary free cortisol
Late night salivary cortisol- normally cortisol production would be low but if you have high cortisol production at night- Cushing’s syndrome
2) Establish source of cortisol excess
- Measure ACTH
Undetectable- carry out Adrenal CT scan
Normal/ High- carry out CRH (corticotrophin) stimulation test:
- No change in ACTH- CT chest
- Exaggerated rise in ACTH- pituitary MRI
what is the management of Cushing’ syndrome
Surgical
- Transphenoidal pituitary surgery
- Laparoscopic adrenalectomy
- Removal of ACTH source (lobectomy if in lung)
Medical (bridge to surgery or people who can’t have surgery)
Metyrapone/ketoconazole
- Inhibit cortisol production
- Short term measure
what is Iatrogenic Cushing’s syndrome
Due to prolonged high dose steroid therapy
eg. asthma, rheumatoid arthritis, inflammatory bowel disease, transplants
Usually oral therapy
Can occur with high dose inhaled steroids or steroid injections
How does adrenal suppression occur in Iatrogenic Cushing’s syndrome
- Long term steroid treatment suppresses ACTH production (negative feedback to anterior pituitary)
- Atrophy of adrenal cortex
- -> no cortisol production
what is the management of Iatrogenic Cushing’s syndrome
Gradual withdrawal of steroid therapy (weeks, months)
what is primary aldosteronism
- Commonest cause of 2ndary hypertension
Autonomous production of aldosterone independent of its regulators (angiotensin II/potassium)
Due to either single adrenal adenoma or bilateral adrenal nodules
what are the clinical features of primary aldosteronism
Significant hypertension
Hypokalaemia (in up to 50%)
Alkalosis
what is the diagnosis of primary aldosteronism
Biochemistry
- Plasma aldosterone elevated
- Plasma renin concentration suppressed
Suppression testing
- Intravenous saline load
Adrenal CT scan
what is the management of primary aldosteronism
Surgical
- Unilateral laparoscopic adrenalectomy
- Only if adrenal adenoma
- Cure of hypokalaemia
- Cures hypertension in 30-70% cases
Medical
- In bilateral adrenal hyperplasia
- Use MR (mineralcorticoid) antagonists (spironolactone or eplerenone)
- Or amiloride (blocks Na reabsorption by kidney)
What is Phaeochromocytoma
Catecholamine secreting tumours of the adrenal medulla (catecholamine excess- intermittent excess so comes in surges)
- Pale sweating with palpitations
what is the diagnosis and treatment of Phaeochromocytoma
Diagnosis:
Measure urinary catecholamines and metabolites
CT scan of adrenals
Management:
Adrenalectomy
Pre-operative medicines- α1 +/- β1 antagonists to block effects of catecholamine surge (block a1 first and then B1 with alpha and beta blockers)
