Electrolytes

Question 1

most important electrolyte abnormalities to know about

Answer 1

hypercalcaemia
Hyperkalaemia
hyponatraemia

Question 2

ECG changes seen in Hyperkalaemia

Answer 2

low flat p waves
tall tended T waves
broad QRS
up slurring into ST segment

Question 3

causes of Hyperkalaemia

Answer 3

AKI/CKD
K+ rich diets
drug induced 
hypoaldosteronism 
increased release from cells (DKA, rhabdomyolysis, strenuous exercise, tumour lysis)

Question 4

drugs which cause Hyperkalaemia

Answer 4

ACEi/ARB
spironolactone
heparin/LMWH
trimethoprim 
beta blockers

Question 5

treatment of Hyperkalaemia

Answer 5

calcium gluconate (10mls 10%)
ECG monitoring
IV insulin (10 units)+ dextrose (50mls 50%)
salbutamol nebuliser

Question 6

how do you treat Hyperkalaemia for people on dialysis

Answer 6

treated with their regular dialysis

Question 7

causes of Hypercalcaemia

Answer 7

primary hyperparathyroidism 
malignancy 
granulomatous disease
drugs
immobilisation (due to bone and mineral loss) 
drugs (vit D, lithium, thiazides) 
thyrotoxicosis
familial hypercalciuric hypercalcaemia

Question 8

treatment for Hypercalcaemia

Answer 8

fluids -IV NaCl 0/9% 4-6L/24 hours

bisphosphonates - only licensed for tumour induced hypercalcaemia

Question 9

clinical features of hypercalcaemia

Answer 9

(bones, stones, groans, psychiatric moans)

• bone pain
• renal stones
• mood distrubance
• abdo pain - nausea & constipation

Question 10

ECG changes in hypercalcaemia

Answer 10

shortened QT interval 
bloods- FBC, renal core, bone profile, PTH
myeloma screen
CXR
serum ACE

Question 11

causes of hypernatraemia

Answer 11

excess water loss:

• skin - sweating/burns
• gut- diarrhoea, vomiting, fistulae
• renal- diuretics, diabetes insidious, osmotic diuresis

Question 12

what is osmotic diuresis

Answer 12

increased urine production to get rid of substances in blood eg. glucose in DKA

Question 13

how do you calculate serum osmolality

Answer 13

2x Na + urea + glucose

Question 14

treatment for hypernatraemia

Answer 14

oral rehydration (oral water/glucose 5%)
IV dextrose

Question 15

at what rate should you reduce serum Na and what happens if its reduced to fast

Answer 15

no more than 10mmol/24 hours

if reduced too quickly can cause rapid brain expansion and tentorial herniation

Question 16

causes of hypokalaemia

Answer 16

loop and thiazide diuretics
D&V
re-feeding syndrome

Question 17

treatment of hypokalaemia

Answer 17

oral replacement - K tablets

IV replacement - rate of infusion should not exceed 10mmol/hour

Question 18

how does hypocalcaemia present

Answer 18

muscle cramps
parasthesia
tetany
carpopedal spasm

Question 19

treatment of hypocalcaemia

Answer 19

oral calcium supplement
vit D supplement

if severe (<1.9)

• caclium gluconate 10% in 5% glucose
• follow with continuous IV infusion

Question 20

ECG presentation of hypocalcaemia

Answer 20

QT prolongation

cardiac monitoring

Question 21

what other electrolyte should you also check in hypoclacaemia

Answer 21

magnesium (can also be low)

Question 22

whats the first thing you do in hyponatraemia

Answer 22

check serum osmolarity

if serum osmolarity low - asses fluid stasis

if serum osmolarity high - could be hyperglycaemia (or pseudo causes)

Question 23

causes of hyponatraemia when urine sodium is also low

Answer 23

acute water overload
malnutrition
polydipsia

Question 24

causes of hyponatraemia when urine sodium is high

Answer 24

glucocorticoid deficiency (Addisons disease)
SIADH
ACTH
hypothyroidism

Question 25

causes of low sodium in fluid overload

Answer 25

cardiac failure
nephrotic syndrome
liver cirrhosis

Question 26

causes of low sodium in hypovolaemia with low urinary sodium

Answer 26

vomiting 
diarrhoea
pancreatitis
burns
sweating

Question 27

cause of low sodium in hypovolaemia with high urinary sodium

Answer 27

diuretics
salt wasting nephropathy
cerebral salt wasting
mineralocorticoid deficiency