electrolyte abnormalities

Question 1

what are the causes of hyponatraemia?

Answer 1

diuretics
diarrhoea
heart failure
liver disease
renal disease
SIADH

Question 2

what are the clinical features of hyponatraemia?

Answer 2

neurologic- osmotic shift of water INTO brain cells causing oedema

headache
confusion
stupor
seizures
coma

Question 3

what are the causes of hypernatraemia?

Answer 3

dehydration- sweating, v, d, diuretics
diabetes insipidus
hyperaldosteronism

Question 4

what are the clinical features of hypernatraemia?

Answer 4

thirst

neurologic- osmotic shift of water OUT of brain cells
confusion
neuromuscular excitability
seizures
coma

Question 5

what are the causes of hypercalcaemia?

Answer 5

primary hyperparathyroidism
malignancies

Question 6

what are the clinical features of hypercalcaemia?

Answer 6

polyuria
constipation
muscle weakness
confusion
coma

Question 7

what are ECG changes in hypercalcaemia?

Answer 7

short ST/QT
wide T waves

Question 8

what are the causes of hypocalcaemia?

Answer 8

acute pancreatitis
pancreas surgery
alkalosis- hyperventilation
rhabodmyolysis
septicaemia
osteolytic metastases
abnormal ca absoprtion (GI) + resorption (urine)
renal failure
small bowel syndrome
parathyroid gland surgery
drugs- bisphosphonates, calcitonin, phenytoin, phosphate substitution, foscarnet

Question 9

what are the clinical features of hypocalcaemia?

Answer 9

paraesthesias
tetany
seizures
encaphalopathy
heart failure

Question 10

what are ECG changes in hypocalcaemia?

Answer 10

prolonged ST/QT

Question 11

what are the causes of hyperkalaemia?

Answer 11

renal failure
insufficient corticosteroid substitution
acidosis
haemolysis
massive muscle damage
insulin deficiency
addison’s disease
drugs- potassium-sparing diuretics, ACEi, ARB, digoxin

Question 12

what are clinical features of hyperkalaemia?

Answer 12

neuromuscular- muscle weakness + cardiac toxicity -> VF/asystole

Question 13

what are ECG changes in hyperkalaemia?

Answer 13

wide flat P waves
prolonged PR interval
wide QRS
ST elevation in V1-V3
pointed T waves
sine waves- fusion of QRS + T waves

Question 14

what are causes of hypokalaemia?

Answer 14

diarrhoea
excess vomiting
alcoholism
malnutrition
primary or secondary aldsosteronism
drugs- liquorice, glucose infusion, diuretics, adrenergic agonists, theophylline, corticosteroids, insulin

Question 15

what are clinical features of hypokalaemia?

Answer 15

muscle weakness -> paralysis + resp failure
cramping
fasciculations
paralytic ileus
hypoventilation
hypotension
tetany
rhabdomyolysis

Question 16

what are ECG changes in hypokalaemia?

Answer 16

p wave amplitude/duration/PR interval increase
ST depression
Flat + wide T waves or TWI
U waves V2-V3

Question 17

what are the causes of hypermagnesaemia?

Answer 17

rare
renal failure after ingestion of mg containing drugs eg antacids/purgatives
hypothyroidism/addison’s disease

Question 18

what are clinical features of hypermagnesaemia?

Answer 18

hypotension
respiratory depression
cardiac arrest

Question 19

what are ECG changes in hypermagnesaemia?

Answer 19

prolonged PR interval
widening QRS
complete heart block/aystole

Question 20

what are the causes of hypomagnesaemia?

Answer 20

inadequate mg intake
increased excretion due to hypercalcaemia or drugs like furosemide

Question 21

what are clinical features of hypomagnesaemia?

Answer 21

often due to accompanying hypokalaemia + hypocalcaemia

lethargy, tremor, tetany
seizures, arrythmias

Question 22

what are ECG changes in hypomagnesaemia?

Answer 22

tall T wave
ST depression
SVT/VT