Electrolyte imbalance Flashcards
what are the causes of hyponatraemia with a urinary Na < 20mmol/l?
extra-renal causes;
- diarrhoea, vomiting, sweating, burns
water excess;
- secondary hyperaldosteronism
- nephrotic syndrome
- IV dextrose
- psychogenic polydipsia
what are the causes of hyponatraemia with a urinary Na > 20mmol/l?
renal causes;
- renal failure
- cerebral salt wasting syndrome
- salt wasting nephropathy
- diuretics
- addisons disease
euvolaemic patients;
- hypothyroidism
- SIADH
what are the causes of hyponatraemia with a normal serum osmolarity?
pseudohyponatraemia
- hyperproteinaemia
- hyperlipidaemia
what are the causes of hyponatraemia with a high serum osmolarity?
hyperglycaemia
alcohol
mannitol
how would you treat a patient with severe hyponatraemia?
bolus hypertonic saline with or without conivaptan (vasopressin/ADH)
at what Na level is hyponatraemia?
Na < 135 mmol/l
at what Na level is hypernatraemia?
Na > 145 mmol/l
what are causes of hypernatraemia?
HHS dehydration Conn's syndrome Cushing's syndrome Liddle's syndrome 11 beta hydroxyls deficiency
a patients test results show; - serum Na > 135 - urinary Na > 20 - urinary osmolarity > 500 the patient has a normal lying and standing BP
what is the most likely cause of the hyponatraemia?
SIADH
what are causes of SIADH?
malignancy respiratory - TB - pneumonia neurological - SAH - subdural haematoma - meningitis drugs - carbamazepine - cyclophosphamide - NSAIDS - SSRI
what are ECG features of hyperkalaemia?
tall tented T waves
small P waves
widening of QRS
what are the ECG features of hypokalaemia?
U waves small/absent T waves prolonged PR interval ST depression long QT
how is hyperkalaemia treated?
shift K from extravascular to intracellular
- insulin
- neb b2 agonists salbutamol
stabilise cardiac membrane;
- IV calcium gluconate
remove K from body;
- rectal calcium resonium
- loop diuretics
- dialysis
how is hypocalcaemia treated?
mild/moderate - NaCl fluids
severe - IV calcium gluconate 10ml of 10% solution over 10 minutes
how is hypercalcaemia treated?
rehydration with 0.9% NaCl
following hydration give bisphosphonates or calcitonin
what are signs of hypocalcaemia?
chvostek sign
trousseau’s sign
prolonged QT interval on ECG
what ECG changes are found in hypercalcaemia?
shortening of QT interval
what is the normal range of calcium level?
2.1 - 2.6 mmol/l
what are the causes of hypercalcaemia?
primary hyperparathyroidism malignancy - bones - SCC lung cancer - myeloma addisons disease
what are causes of hypocalcaemia?
CKD vitamin D deficiency hypoparathyroidism acute pancreatitis pseudohypoparathyroidism contamination of sample with EDTA
what are causes of hyperkalaemia?
addisons metabolic acidosis drugs: ACEI, ARB, spironolactone AKI rhabdomyolysis
what are the causes of hypokalaemia?
with acidosis;
- vomiting
- thiazide like diuretics
- conns syndrome
- cushings syndrome
with alkalosis
- diarrhoea
- partially treated DKA
- renal tubular acidosis
