Endo Flashcards
What is the aetiology of secondary adrenal insufficiency?
- Iatrogenic due to long-term steroid therapy
- Hypothalamic-pituitary disease resulting in decreased ACTH production
What is the pathophysiology secondary adrenal insufficiency?
- Reduction in ACTH release causing decreased cortisol
What is the presentation of secondary adrenal insufficiency?
- Vague symptoms of feeling unwell
- No skin hyperpigmentation
How many secondary adrenal insufficiency investigated?
- ACTH level are low
- Mineralocorticoid production intact
How is secondary adrenal insufficiency managed?
- Oral hydrocortisone
- Should recover if long-term steroids are slowly weaned off
What is the aetiology of hyperkalaemia?
- Acute self-limiting occurs normally after vigorous exercise
- Decreased exertion – AKI, drugs (ACEi, NSAID, potassium-sparing diuretics)
- Redistribution (intra to extracellular) – diabetic ketoacidosis, metabolic acidosis, tissue necrosis
- Increased load (potassium chloride, transfusion of stored blood)
What is the pathophysiology of hyperkalaemia?
- When K+ levels in the blood rise, it reduces the difference in electrical potential between cardiac myocytes and the outside of cells
- Decreased action potential threshold abnormal action potentials and abnormal heart rhythms
- Can result in VF and cardiac arrest
What is the presentation of hyperkalaemia?
- Asymptomatic until K+ is high enough to cause cardiac arrest
- Fast irregular pulse
- Chest pain
- Weakness
- Light-headedness
- Muscle weakness and fatigue
- May be associated with metabolic acidosis therefore Kussmaul’s respiration (low, deep, sighing inspiration and expiration)
What are the differential diagnoses of hyperkalaemia?
- Haemolysis
- Contamination with K+ EDTA anticoagulant
- Thrombocythaemia
How is hyperkalaemia investigated?
- Serum K+ > 5.5mmol/L
- Serum K+ > 6.5mmol/L = medical emergency
- Progressive ECG abnormalities (tall, tented T waves, small P waves, wide QRS complex)
How was hyperkalaemia managed? (non-urgent and urgent management)
NON-URGENT – treat underlying cause, review meds (esp ACEi, NSAIDs), dietary K+ restriction, can give polystyrene sulfonate resin
URGENT – IV 10ml 10% calcium gluconate, soluble insulin, glucose, IV salbutamol
What is the aetiology of hypokalaemia?
- Increased renal excretion (thiazide/loop diuretics, increased aldosterone secretion, exogenous mineralocorticoids, renal disease)
- Reduced dietary K+ intake
- Redistribution to cells (beta-agonists, salbutamol, acute MI)
- GI losses (vomiting, severe diarrhoea, laxative abuse)
What is the presentation of hypokalaemia?
- Usually asymptomatic
- Muscle weakness
- Cramps
- Hypotonia
- Hyporeflexia
- Tetany (intermittent muscle spasms/ cramps)
- Palpitations
- Light-headedness
- Arrhythmias
- Constipation
How is hypokalaemia investigated?
- Serum K+ < 3.5mmol/L
- Serum K+ < 2.5mmol/L = medical emergency
- ECG (flat/inverted T waves, increased QT, visible U waves, ST depression)
How is hypokalaemia managed? (initial management as well as management for mild and severe cases)
- Identify and treat and underlying cause
- Acute can self-resolve usually after stopping diuretics/ laxatives
- MILD – oral K+ supplements (+ K+ sparing diuretic if on thiazide diuretic)
- SEVERE – IV K+ cautiously
What is the aetiology of syndrome of inappropriate secretion of ADH?
- Tumours
- Pulmonary lesions
- Alcohol withdrawal
- Drugs (e.g. carbamazepine)
- CNS causes (meningitis, tumours, head injury, SLE)
What is the pathophysiology of syndrome of inappropriate secretion of ADH?
Continuous secretion of ADH despite plasma being very dilute, leading to retention of water (increased aquaporin-2 channels) and excess blood volume, therefore hyponatraemia
What is the presentation of syndrome of inappropriate secretion of ADH?
- Symptoms as a result of hyponatraemia
- Varied and generic
- Anorexia/ nausea and malaise
- Weakness and aches
- Reduced GCS, confusion and drowsiness
- Fits and coma (later)
How is syndrome of inappropriate secretion of ADH investigated?
- Serum: low sodium, low plasma osmolality
- Urine: high sodium, high osmolality
- Normal renal, adrenal and thyroid function
How is syndrome inappropriate secretion of ADH managed?
- Treat underlying cause
- Restrict fluid intake
- Hypertonic saline is very symptomatic
- Oral demeclocycline
- Vasopressin antagonist (e.g. oral tolvaptan)
- Salt and loop diuretic (e.g. oral furosemide)
What is the aetiology of cranial diabetes insipidus?
idiopathic, congenital defects in ASH gene, hypothalamus disease, tumour, trauma, infiltrative disease
What is the aetiology of nephrogenic diabetes insipidus?
hypokalaemia, hypocalcaemia, drugs, renal tubular acidosis, sickle cell disease, familial mutation of ASH receptor
What is the general pathophysiology of diabetes insipidus?
Reduced ADH secretion or impaired response to ADH results in significant water losses and therefore dilute urine
What is the main risk factor of diabetes insipidus?
Family history
