Adrenal Disease Flashcards
What are the two regions of the adrenal gland?
=> Adrenal cortex - outer region, contains
- Zona Glomerulosa => releases mineralcorticoids (outermost)
- Zona Fasiculatis => releases glucocorticoids
- Zona Reticularis => releases androgens (innermost)
=> Adrenal medulla - inner region releases catecholamines (Adr and NA)
What is the HPA axis?
- Hypothalamus secretes CRH (corticotrophin releasing hormone) which stimulates the anterior pituitary
- Anterior pituitary releases ACTH
- ACTH acts on the adrenal gland, causing release of cortisol
What is Cushing’s Syndrome?
- Due to persistent excess circulating glucocorticoids
=> Common presentations:
- Weight gain
- Moon face
- Proximal muscle weakness
- Gonadal dysfunction
=> Cushings DISEASE refers to an increase in glucocorticoids level because of a central pituitary problem where as Cushings SYNDROME refers to glucocorticoid increase from anywhere in the body or exogenous
What are the causes of Cushing’s syndrome?
=> Exogenous administration of glucocorticoids
- Causes adrenal atrophy due to negative feedback
=> Pituitary adenoma secreting ACTH (Cushings Disease)
=> Adrenal cortical adenoma
- Tumour arises from the zona fasiculata
- Secretes cortisol
=> Paraneoplastic syndrome - small cell lung cancer
- Tumour cells of small cell lung cancers secrete ACTH
- Presents with hypokalemic metabolic alkalosis (as high levels of cortisol result in mineralcorticoid activity), weight loss, hyperglycaemia
What are the causes of Primary Hyperaldosteronism, investigations and management?
=> Bi-lateral idiopathic adrenal hyperplasia
- Treated via Spironolactone or Amiloride
=> Aldosterone producing adrenal cortical adenoma
- Conn’s Syndrome
- Treatement involves laproscopic removal
=> Investigations:
- Renin:Aldosterone ratio (high Ald low Ren) FIRST LINE
- CT abdomen and adrenal vein sampling to determine if uni or bi lateral
What is Phaechromocytoma?
Neuroendocrine tumour of the adrenal medulla
- Excess release of adrenaline, causing high blood pressure
What are the symptoms of Phaechromocytoma?
=> Usually asymptomatic
- Throbbing headache
- Sweating
- Palpitations
What is the specific investigation phaecochromocytoma and management?
=> 24 hour urinary collection
- Measure adrenaline and noradrenaline levels
=> PASSMED states 24 hour urinary metanephrines should be measured
=> Management:
- Medical management is first line (alpha blocker or B blocker) to control BP
- Surgical removal of tumour
What germ-line mutations may phaecochromocytoma be associated with?
- RET gene
- NF1 gene
- VHL gene
- SDH8 SDHC and SDHD genes
What are the investigations in suspected Cushings Syndrome?
=> 1st line - Overnight Dexamethasome Test or 24hr urinary cortisol
- Dexamethasone given
- Serum cortisol measured next morning
- No suppression means Cushings Syndrome. As if the problem was pituitary it would have decreased its activity in response to the high dexamethasone (which is a glucocorticoid)
=> 2nd line - 48hr Dexamethasone suppression test or 48hr high dose Dexamethasone suppression test
- No suppression of Cortisol indicates Cushings Syndrome
- Suppression indicates Cushings disease
What is Addison’s disease?
- Autoimmune adrenal destruction
- Results in reduced cortisol and aldosterone secretion
A FOR ADRENAL INSUFFICIENCY
What are the clinical features of Addison’s disease?
- Lethargy, weakness, weight loss, ‘salt-craving’, nausea & vomiting
- Hyperpigmentation, vitiligo, loss of pubic hair, hypoglycaemia, hypotension
- Hyponatremia and hyperkaelemia
=> Only Primary Addison’s disease sees hyperpigmentation
What are the causes of Addison’s disease?
=> Primary:
- Tuberculosis
- HIV
- Metastases
- Meningiococal septicecmia
- Antiphospholipid syndrome
=> Secondary:
- Pituitary disorders
What is the main investigation in suspected Addison’s disease?
=> Short Synthacen Test - (Synthacen = synthetic ACTH)
- Measure cortisol levels before and after test
- After synthacen infusion, if cortisol levels rise, it means Addison’s unlikely
- If cortisol levels low, then Addison’s disease as there is nothing to produce cortisol (adrenals have been destroyed)
=> 21-hydroxylase adrenal antibodies
- Positive
What is the management of Addison’s disease?
Glucocorticoid (hydrocortisone) and mineralcorticoid (fludrocortisone) therapy should both be given
