L17: Adrenal Disorders Flashcards
(22 cards)
Describe 5 ways in which we can measure adrenal cortical function
- Plasma cortisol & ACTH levels
- 24 hr urinary excretioin of cortisol and its breakdown products (e.g. 17-hydroxysteroids)
- Dynamic tests: e.g. dexamethasone supression and ACTH stimulation tests
- Electrolytes: high K+ in adrenal hormone deficiency, low k+ in adrenal hormone excess. In ACTH deficiency only Na+ low
- Radiological assessments
State when you would test cortisol levels if you suspect it to be:
- Low
- High
- Low: test when meant to be high (morning e.g. 9:00am)
- High: test when meant to be low (e.g. 0:00)
Describe the dexamethasone test
- Dexamethasone is a synthetic steroid hormone that would normally supress secretion of ACTH and therefore cortisol
- If supression >50% occurs = Cushing’s disease
- Supression doesn’t occur= adrenal tumour or ectopic ACTH production
Describe the synacthen test
Synacthen is a synthetic analogue of ACTH hence it usually increases plasma cortisol.
If it raises plasma cortisol >200nm/L then it excludes addisons disease
What is Cushing’s syndrome?
Describe signs & symptoms
- Hyperglycaemia: increased muscle proteolysis & gluconeogenesis leads to associated polyuria and polydipsia
- Thin arms and legs: increased muscle proteolysis
- Abdominal obesity, buffalo hump and and moon face: increase lipogenesis
- Purple striae on lower abdomen, upper arms and thighs: weakend protein in skin leading to thinning of skin an easy bruising
- Back pain and collapse of ribs: osteoporosis
- Hypertension: cortisol can have mineralocorticoid effects
- Increased suscepctibility to infections and acne: immuosupressive, anti-inflammatory, anti-allergic actions of cortisol
Describe external and endogenous causes of Cushing’s syndrome
What must you be aware of when a patient is stopping prescribed glucocorticoids/steroids?
Steroid dosage must be gradually reduced as cortex will be downregulated
Explain the difference between Cushing’s syndrome and Cushing’s disease
- Cushing’s syndrome: collection of symptoms due to chronic excessive exposure to cortisol
- Cushing’s disease: specific case of benign ACTH secreting pituitary adenoma
What is Addison’s disease?
State 2 possible causes
Primary adrenal gland failure/chronic adenal insufficiency. Causes:
- Disease of adrenal cortex e.g. autoimmune destruction
- Disorders of pituitary or hypothalamus leading to decreased secretion of ACTH or CRF
Disorders of adrenal cortex may cause….(2)
- Life threatening emergency Addisonian crisis
- Addison’s disease
What is the most common cause of Addison’s disease?
Autoimmune
Rarer causes: fungal infection, adrenal cancer, adrenal haemorrhage
Describe signs and symptoms of Addison’s disease
How do we treat it?
Signs and symptoms:
- Postural hypotension
- Lethargy
- Weight loss
- Anorexia
- Increased skin pigmentation
- Hypoglycaemia
Treatment: glucocorticoids & mineralocorticoid replacement & education to prevent crisis
Describe why you get hyperpigmentation in Addison’s disease
Describe how you can use ACTH levels and follow up dynamic tests to find cause of problem
For an addisonian crisis, state:
- What it is
- Symptoms
- Risk factors
- Treatment
What is congenital adrenal hyperplasia?
What are consequences?
- Defect in one or more of enzymes required fro synthesis of corticosteroids from cholesterol leading to lack of cortisol and increased ACTH secretion which causes hyperplasia of adrenal cortex
- Most commonly affected enzyme: enzyme 21-hydroxylase- decreases glucocorticoids and mineralocorticoids
- Precursors for these hormones diverted to more androgen synthesis which leads to genital ambiguity in femal infants and salt wasting crisis due to high sodium excretion
What is hyperaldosteronism?
Too much aldosterone produced
Describe primary and secondary hyperaldosteronism
State signs and symptoms of both
State treatment
What do androgens do?
What are consequences of over secretion in females?
Androgens stimulate growth of male genital tract and male secondary characteristics
- Oversecretion in females:
- Hirsutism (excessive body hair)
- Menstrual problems
- Virilisation (abnormal male like charcteristics in female)
Oestrognes decrease circulating levels of cholesterol; true or false
True
What is a phaemochromocytoma?
Symptoms?
Rare catecholamine secreting (mainly NA) tumour in chromaffin cells. Symptoms:
- Severe hypertension
- Headaches
- Anxiety
- Palpitations
- Diaphoresis
- Weight loss
- Elevatd blood glucose/glucose intolerance
