20. Adrenal disorders Flashcards
What are the clinical presentation of adrenal hormone deficiencies?
• Cortisol: ACTH excess from pituitary
weakness, tiredness, weight loss, hypoglycaemia
- Mineralocorticoid: dizziness, low Na, high K
- Androgen: low libido and loss of body hair in women
What are the clinical presentation of adrenal hormone excess?
- Cortisol: weight gain and cushingoid features
- Mineralocorticoid: high BP and low K
- Androgen: increased male characteristics in women
What is the clinical presentation of ACTH excess?
Skin pigmentation melanocyte stimulation
In what conditions is hyper-pigmentation seen?
pigmentation seen in Addison’s and ACTH-driven cushings
What is the clinical presentation of catecholamine excess?
- Acute episodes
- Sweating
- Anxiety
- Palpitations
- High or low BP
- Collapse
- Sudden death
What are the biochemical assessments for suspected adrenal cortex deficiency and what would they show?
- Electrolytes: low Na, high K in aldosterone deficiency*
- 09:00 basal cortisol: low - when it should be high
- Stimulation test: inject synthetic ACTH (synacthen)
*in ACTH deficiency only Na is low but K is normal
What is used in a stimulation test for the HPA (adrenal) axis?
Synthetic ACTH: synACTHen
What are the biochemical assessments for suspected adrenal cortex excess and what would they show?
- Electrolytes: high BP, low K
- Midnight cortisol: high - should be low
- 24h urine cortisol: high
- Suppression test: failure to suppress
- Androgens and derivatives: high
What is used in suppression test for HPA adrenal axis?
Dexamethasone (steroid which provides negative feedback to reduce ACTH)
Describe the dexmethasone suppression test
• Dexamethasone is a potent synthetic steroid that, when given orally would normally suppress (by feedback inhibition) the secretion of ACTH and thus cortisol.
• If Dexamethasone suppresses of plasma cortisol
by >50% , it indicates Cushing’s disease because for the diseased pituitary, even though it is relatively insensitive to cortisol, it does retain some sensitivity to potent synthetic steroids. Thus suggesting that excess cortisol is produced from the pituitary.
• Suppression does not normally occur in adrenal tumours or ectopic ACTH production.
What would the synacthen test tell us?
The administration of Synacthen (a synthetic analogue of ACTH) intramuscularly, would normally increase plasma cortisol by >200 nmol/L. A normal response usually excludes Addison’s disease.
Compare high and low dose dexmethasone test
Low dose test done to see if the patient has cushing’s syndrome
- low cortisol –> normal
- high/normal cortisol –> cushing’s syndrome
high dose test done to see what might be causing cushing’s syndrome
- low cortisol –> cushing’s disease
- high/normal cortisol –> if ACTH low then adrenal cushings, if ACTH high then ectopic tumour producing ACTH
What are the biochemical assessments for suspected adrenal medulla excess?
24h urine catecholamines: adrenaline, noradrenaline, dopamine, 3-Methoxy-Tyramine
24h urine metanephrines: (metabolites of adrenaline and noradrenaline) metadrenaline, normetadrenaline
Plasma metanephrines: more sensitive than 24h urine
What should be avoided before biochemical assessment of catecholamines?
Avoid certain foods before collection
coffee, coke, bananas, chocolate, vanilla
-false positives
What radiological techniques can be used in assessment of adrenal disease?
CT, MRI, MIBG, PET,
What is the main cause of Addison’s disease?
Auto-immune
What are the symptoms of Addison’s disease?
- Fatigue • Weakness • Anorexia • Weight loss
- Nausea • Abdominal pain • Dizziness
- Pigmentation
What are the signs of Addison’s disease?
- Underweight • Signs of weight loss
- General malaise • Other auto-immune disease
- Vitiligo • Thyroid • Postural hypotension
- Pigmentation
What are some causes of primary adrenal failure (addisons)?
- Auto-immune: isolated or polyglandular
- Infection: TB, fungal, AIDS
- Infiltration: amyloid, haemochromatosis
- Malignancy: lung, breast, kidney
- Genetic: CAH, adreno-leukodystrophy
- Vascular: haemorrhage or infarction
- Iatrogenic: adrenalectomy, drugs
What is adrenal crisis?
Exaggerated form of adrenal insufficiency. Usually occurs in a patient with chronic adrenal insufficiency who undergoes stress (trauma, ischemia, surgery)
What are the clinicial features of adrenal crisis?
- Collapse • Hypotension • Dehydration
* Pigmentation • Coma
What is the treatment for adrenal crisis?
- Rapid rehydration with fluids
- Intravenous hydrocortisone
- Correction of hypoglycaemia
- Search for precipitating cause
What is the maintenance treatment for addisons disease?
Glucocorticoid: hydrocortisone, prednisolone
Mineralocorticoid: fludrocortisone