Adrenal Disorders Flashcards
(35 cards)
What are some features of Addison’s disease?
- Lethargy
- Weakness
- Anorexia
- Nausea & Vomiting
- Weight loss, ‘salt-craving’
- Hyperpigmentation (especially palmar creases), vitiligo, loss of pubic hair in women
- Hypotension
- Hypoglycaemia
What are some causes of Addison’s disease?
Primary causes
- Autoimmune destruction of the adrenal glands is the commonest cause of primary hypoadrenalism in the UK, accounting for 80% of cases.
- Tuberculosis
- Metastases (e.g. bronchial carcinoma)
- Meningococcal septicaemia (Waterhouse-Friderichsen syndrome)
- HIV
- Antiphospholipid syndrome
Secondary causes
- Pituitary disorders (e.g. tumours, irradiation, infiltration)
- Exogenous glucocorticoid therapy
How is Addison’s disease managed?
Both Glucocorticoid and Mineralocorticoid replacement therapy as combination of:
- Hydrocortisone: usually given in 2 or 3 divided doses. Patients typically require 20-30 mg per day, with the majority given in the morning dose
- Fludrocortisone
How are patients educated in regards to their Addison’s disease?
- Emphasise the importance of not missing glucocorticoid doses o
- Consider MedicAlert bracelets and steroid cards
- Discuss how to adjust the glucocorticoid dose during an intercurrent illness
- Glucocorticoid dose should be doubled in simple terms
What are some precipitating factors of an Addisonian Crisis?
- Sepsis or Surgery causing an acute exacerbation of chronic insufficiency (Addison’s, Hypopituitarism)
- Adrenal haemorrhage e.g. Waterhouse-Friderichsen syndrome (fulminant meningococcaemia)
- Steroid withdrawal
What are symptoms of Addisonian Crisis?
- Collapse
- Shock
- Pyrexia
What are some electrolyte imbalances experienced thin an Addisonian Crisis?
- Hyponatraemia
- Hyperkalaemia
- Hypoglycaemia
How is Addisonian Crisis managed?
- IV Hydrocortisone 100 mg
- 1 litre normal saline infused over 30-60 mins or with dextrose if hypoglycaemia
- Continue hydrocortisone 6 hourly until the patient is stable
- Oral replacement may begin after 24 hours and be reduced to maintenance over 3-4 days
What is more common: endogenous or exogenous causes of Cushing’s syndrome?
Exogenous causes of Cushing’s more common than endogenous ones.
What are some causes of Cushing’s syndrome?
ACTH dependent causes
- Cushing’s disease (80%): pituitary tumour secreting ACTH producing adrenal hyperplasia
- Ectopic ACTH production (5-10%): e.g. small cell lung cancer
ACTH independent causes
- Iatrogenic: steroids
- Adrenal adenoma (5-10%)
- Adrenal carcinoma (rare)
- Carney complex: syndrome including cardiac myxoma
- Micronodular adrenal dysplasia (very rare)
What is Pseudo-Cushing’s syndrome?
- Often due to alcohol excess or severe depression
- False positive dexamethasone suppression test or 24 hr urinary free cortisol
- Insulin stress test is used to differentiate between true Cushing’s and pseudo-Cushing’s
What are clinical features of Cushing’s syndrome?
Cushing’s syndrome
- Moon face
- Buffalo hump
- Striae
- Weak muscles
- Acne
- Fragile skin
- High Blood pressure
- Weight gain
Who do blood results show in Cushing’s syndrome?
- Hypokalaemic metabolic alkalosis
- Impaired glucose tolerance
- Ectopic ACTH secretion (e.g. secondary to small cell lung cancer) is characteristically associated with very low potassium levels
What are definitive investigations for Cushing’s syndrome?
- 24 hr urinary free cortisol
- The first-line localisation is 9am and midnight plasma ACTH (and cortisol) levels. If ACTH is suppressed then a non-ACTH dependent cause is likely such as an adrenal adenoma
- Overnight dexamethasone suppression test (most sensitive)
- Both low- and high-dose dexamethasone suppression tests may be used to localise the pathology resulting in Cushing’s syndrome.
How is low- and high-dose ODST interpreted?
These tests may be interpreted as follows:
- Not suppressed by low-dose dexamethasone: Cushing’s syndrome not due to primary causes, i.e. likely secondary to corticosteroid therapy
- Not suppressed by low-dose, but suppressed by high-dose dexamethasone indicates Cushing’s disease
- Not suppressed by low- or high-dose dexamethasone indicates ectopic ACTH syndrome likely
What is Phaeochromocytoma?
- Phaeochromocytoma is a rare catecholamine secreting tumour.
- It is a neuroendocrine tumour of chromaffin cells of the adrenal medulla.
What are symptoms of Pheochromocytoma?
- Hypertension (around 90% of cases, may be sustained)
- Headaches
- Palpitations
- Sweating
- Anxiety
What are the investigations of Pheochromocytoma?
- 1st line: 24 hr urinary collection of metanephrines (sensitivity 97%*)
- 2nd line: 24 hr urinary collection of catecholamines (sensitivity 86%)
CT and MRI scanning are both used to localise the lesion.
What is the medical treatment of Pheochromocytoma?
- Phenoxybenzamine: irreversible alpha blockade
- Labetolol: may be co-administered for cardiac chronotropic control.
What is the surgical management of Pheochromocytoma?
- Fluids Perioperatively
- Surgery once medically optimised
- Adrenals are highly vascular structures and removal can be complicated by catastrophic haemorrhage in the hands of the inexperienced
What are factors of a Pheochromocytoma that suggest benign lesions?
- Size less than 3cm
- Homogeneous texture
- Lipid rich tissue
- Thin wall to lesion
What are the causes of Primary Aldosteronism?
- Adrenal Adenoma (Conn’s Syndrome)
- Bilateral idiopathic adrenal hyperplasia
- Adrenal Carcinoma
What are features of Primary Aldosteronism?
- Hypertension
- Hypokalaemia (e.g. muscle weakness)
- Alkalosis
What are investigations of Primary Aldosteronism?
1st line: Plasma aldosterone/renin ratio in suspected primary hyperaldosteronism
- Shows high aldosterone levels alongside low renin levels (negative feedback due to sodium retention from aldosterone) in primary hyperaldosteronism
High-resolution CT abdomen and adrenal vein sampling is used to differentiate between unilateral and bilateral sources of aldosterone excess
