Electrolyte Abnormalities

Question 1

What are some causes of hypocalcaemia?

Answer 1

• Vitamin D deficiency
• Hypoparathyroidism (inherited, post parathyroidectomy)
• Hyperphosphataemia (Tumour lysis syndrome, rhabdomyolysis)
• Acute pancreatitis
• Alkalosis

Question 2

What are the clinical features hypocalcaemia?

Answer 2

SPASMODIC
Spasms,
Peripheral paraesthesia,
Anxiety/irritability
Seizures
Muscle tone increase
Orientation impairment
Dermatitis
Impetigo herpetiformis
Chvostek’s sign

Question 3

What are the investigations for hypocalcaemia?

Answer 3

• ECG
• Bone profile,
• PTH,
• Magnesium,
• Vitamin D
• Amylase
• X-rays

Question 4

What is the management of acute hypocalcaemia?

Answer 4

Mild - Oral calcium supplements
Severe - IV calcium gluconate

Question 5

What are some causes of hypokalaemia

Answer 5

1. Renal (if urine K+ is over 20) eg, diuretics, renal tubular acidosis, cushings)
2. Extra renal (if urine K+ is under 20) g, poor oral intake, gut losses, insulin or alkalosis

Question 6

What are the investigations for hypokalaemia?

Answer 6

ECG, UEs, Chloride, bicarb, glucose and urinary potassium and chloride

Question 7

What is the management for mild hypokalaemia?

Answer 7

Oral slow release potassium chloride, treat the cause and check potassium regularly

Question 8

What is the management for severe hypokalaemia

Answer 8

• Continuous cardiac monitoring,
• Check and correct magnesium as low magnesium causes renal potassium waiting
• IV infusion of 1L saline and 40mmol of potassium chloride
• Avoid glucose and bicarb

Question 9

What are the causes of hyponatraemia?

Answer 9

1. Hypovolaemic - Burns, sweating, D+V, Addison’s disease.
2. Euvolaemic - SIADH or hypothyroidism.
3. Hypervolaemic - Renal failure, heart failure, liver failure or nephrotic syndrome

Question 10

What are the investigations for hyponatraemia

Answer 10

UEs,
Urine and plasma paired osmolalities to show inappropriate sodium conc in urine.
Urine dip
TSH and cortisol to exclude hypothyroidism and Addison’s.

Question 11

What is the management of hyponatraemia?

Answer 11

Hypovolaemic - IV normal saline and treat underlying cause.
Euvolaemic - For SIADH = Fluid restriction, ADH receptor antagonist and oral sodium + furosemide. Hypothyroid - levothyroxine
Hypervolemia - Fluid restriction and treat underlying cause

Question 12

What are some causes of hypomagnasaemia

Answer 12

1. Reduced gut absorption - PPIs, Alcoholism, Diarrhoea
2. Redistribution eg, refeeding syndrome, acute pancreatitis, alcohol withdrawal.
3. Increased renal excretion eg, Diuretics, digoxin, gentamicin

Question 13

What are some complications of hypomagnasaemia?

Answer 13

Weakness,
Paraesthesia,
Seizures,
Coma,
Hypocalcaemia as low Magnesium interferes with PTH release
Ventricular arrhythmias

Question 14

What are some causes of hypercalcaemia?

Answer 14

Primary hyperparathyroidism - Tumour of parathyroid gland.
Tertiary hyperparathyroidism - Occurs due to sustained secondary hyperparathyroidism resulting in hyperplasia of glands.
Malignancy

Question 15

What are the investigtions for hypercalcaemia?

Answer 15

ECG
LFTs
UEs
Bone profile

Question 16

What is the management for hypercalcaemia?

Answer 16

Aggressive IV fluids and Bisphosphonates

Question 17

What are some causes of hyperkalaemia?

Answer 17

Impaired excretion - AKI. CKD, ACE inhibitors, Spironolactone, NSAIDs, Addison’s disease
Increased release from cells - Lactic acidosis, rhabdomyolysis, beta blockers

Question 18

What are the ECG changes seen in hyperkalaemia?

Answer 18

Tall tented T waves, flattened P waves, prolonged PR interval

Question 19

What is the management for hyperkalaemia?

Answer 19

If K+ is between 5.5 and 6.5 then give calcium resonium.
If K+ is >6.5 and/or ECG changes then five calcium gluconate and insulin/dextrose infusion or nebulised salbutamol

Question 20

What are the symptoms of hypernatraemia?

Answer 20

Lethargy, weakness, confusion, agitation, seziures, coma

Question 21

What are the causes of hypernatraemia?

Answer 21

1. Excess water loss - Diabetes insipidus, diurestics, diarrhoea, vomiting, sweating or burns.
2. Excessive hypertonic fluid - IV infusions, total parental nutrition, enteral feeds
3. Decreased thirst - old age or acute illness

Question 22

What is the management of hypernatraeia?

Answer 22

oral or IV fluids

Question 23

What are some causes of hyperphosphataemia and the management

Answer 23

Causes - CKD (most common), TLS, acidosis.
Management - Phosphate binders

Question 24

Describe features of hypophosphataemia

Answer 24

Levels below 2.5 however not clinically significant until levels reach below 0.45

Question 25

What are the causes of hypophosphataemia?

Answer 25

Shifting into cells: refeeding syndrome, resp alkalosis, insulin and hungry bone syndrome.
Increased renal loss: Hyperparathyroidism, impaired Vit D metabolism, renal tubular acidosis.
Reduced gut uptake: Malnutrition, Vit D deficiency, chronic diarrhoea, chronic malabsorption

Question 26

What are the clinical features of hypophosphataemia?

Answer 26

Mainly asymptomatic but when levels drop below 0.45 then seizures, arrhythmia or coma.

Question 27

What is the management of hypophosphataemia?

Answer 27

Oral replacement usually sufficient
Can give IV

Question 28

What are some causes of reduced magnesium absorption?

Answer 28

Reduced gut absorption - PPIs, Alcoholism, TPN, diarrhoea, malabsorption, vomiting, fistulae
Redistribution - refeeding syndrome, insulin administration, alcohol withdrawal.
Increased renal excretion - loop/thiazide diuretics, digoxin, gentamicin,

Question 29

What are the clinical features of low magnesium??

Answer 29

Weakness,
Paraesthesia,
Seizures,
Coma,
Hypocalcaemia,
Hypokalaemia,
Ventricular arrhythmias,
Chondrocalcinosis