Electrolytes

Question 1

What can cause pseudohyponatraemia?

Answer 1

Lab technique
Hyperlipidaemia, hyperproteinaemia (normal serum osmolarity)
Hyperglycaemia, mannitol, excess urea (high serum osmolarity)
Toxic ethanol

Question 2

What are causes of hypovolaemic hyponatraemia with high urinary sodium

Answer 2

Kidneys not retaining sodium + low volume
Diuretics
Vomiting, NG suction

Question 3

What are causes of euvolaemic hyponatraemia with high urinary sodium

Answer 3

All from SIADH

Malignancy, pulmonary issues, drugs (haloperidol, antidepressants, antineoplastic drugs, carbamazepine)

Question 4

What are causes of hypervolaemic hyponatraemia with high urinary sodium

Answer 4

CKD, hypothyroidism

Question 5

What are causes of hypovolaemic hyponatraemia with low urinary sodium

Answer 5

Diarrhoea, sweating, burns, pancreatitis

Question 6

What are causes of euvolaemic hyponatraemia with low urinary sodium

Answer 6

Hypotonic fluids - dextrose, psychogenic polydypsia
Elderly patient with tea and toast diet
Large-volume binge beer drinking

Question 7

What are causes of hypervolaemic hyponatraemia with low urinary sodium

Answer 7

CCF

Liver cirrhosis, low albumin, nephrotic syndrome

Question 8

What are the symptoms of hyponatraemia?

Answer 8

Lethargy, weakness and ataxia
• Nausea and vomiting
• Headache
• Confusion
• Seizures and coma.

Question 9

By how much can sodium be increased in a neurologically stable patient?

Answer 9

0.5 mmol/L/hour

Question 10

How is symptomatic hyponatraemia with neurological instability (confusion, seizures, coma, brain herniation) managed?

Answer 10

Hypertonic saline until neurologically stable followed by slow Na replacement.

Question 11

How is SIADH treated?

Answer 11

Fix underlying cause and withdraw contributing drugs
Fluid restriction
Furosemide with fluid replacement (0.9% saline with KCL)
Demeclocycline is last line

Question 12

How can you adjust sodium measurement for hyperglycaemia?

Answer 12

Adjust the serum sodium up by

1 mmol/L for every 3 mmol/L elevation in BGL.

Question 13

How is hypovolaemia hyponatraemia managed?

Answer 13

Fluid replacement

Question 14

How is hypervolaemia hyponatraemia management?

Answer 14

Diuresis (spironolactone) with fluid restriction

Question 15

How is mild hyponatraemia treated (euvolaemic)?

Answer 15

0.9% NaCl

Question 16

How is mild-moderate hyponatraemia treated (euvolaemic/hypervolaemic)?

Answer 16

Fluid restriction

Question 17

What is the management for severe hyperkalaemia?

Answer 17

Call for help, ECG
10mmol KCl 100ml over 1 hour
40mmol KCl maintenance rate over 3-12 hours
Correct Mg

Question 18

What is the maximum rate of KCl infusion?

Answer 18

10mmol/hour

Question 19

What is the dose of oral KCl supplementation?

Answer 19

KCl SR 1200 to 3600 mg (16 to 48 mmol) orally, daily in divided doses.

Question 20

What is the management for severe hypocalcaemia (<1.5)

Answer 20

Calcium gluconate or calcium chloride (3x stronger)
Oral calcium once stable
Blood every 3-4 hours
Consider Mg correction and vitamin D

Question 21

How is calcium gluconate is given for severe hypocalcamia?

Answer 21

10% 20 ml in 0.9% NaCl 100ml over 20 minutes then

10% 100ml in 0.9% NaCl 900ml at 50 ml/hour

Question 22

What is the management for hypercalcaemia?

Answer 22

IV fluids - 0.9% saline 6L/24 hours
Bisphosphonate (zolendronic acid, pamidronate)
Calcitonin
Glucocorticoids for malignancy, vitamin D and sarcoidosis