Abnormalities in plasma electrolytes

Question 1

What are plasma electrolytes?

Answer 1

Ions in the plasma that contribute to osmotic balance which controls the movement of water between the cells and the interstitium

Question 2

What are the key plasma electrolytes?

Answer 2

• Sodium
• Potassium
• Chloride
• Bicarbonate
• Calcium
• Phosphate

Question 3

What is the major extracellular cation?

Answer 3

Sodium

• Has a major effect on osmotic pressure

Question 4

What is the major intracellular cation?

Answer 4

Potassium

• Has very little effect on osmotic pressure

Question 5

Where is potassium excreted?

Answer 5

Renal tubules - especially DCT and collecting tubles

Question 6

Causes of hyponatremia (low sodium)

Answer 6

• Excess sweating
• Vomiting
• Diarrhoea
• Diuretics
• Acidosis

Question 7

What are some causes of hypernatremia?

Answer 7

• Dehydration
• Diuretics
• Over consumption

Question 8

What happens to Na+ levels in AKI?

Answer 8

Hyponatremia due to a decreased GFR and lack of urine production which causes oedema

Question 9

What is a consequence of hyperkalemia?

Answer 9

Depolarisation of skeletal and cardiac muscle and neurons

Inability to repolarise meaning the heart seizes - can be fatal

Question 10

What affect does insulin have on blood potassium?

Answer 10

Promotes function of the Na/K ATPase and promotes the movement of K+ into cells

Diabetic patients can experience hypokalemia when insulin is adminstered

Question 11

What are the symptoms of hyperkalemia?

Answer 11

• muscle weakness.
• a general feeling of weakness or fatigue.
• nausea
• muscle pain or cramps.
• difficulty breathing.
• unusual heartbeat and chest pains

Question 12

What is the predominant extracellular anion?

Answer 12

Chloride

Question 13

What is the second most abundant anion in the blood?

Answer 13

Bicarbonate

Question 14

What are the consequences of hypercalcemia?

Answer 14

Moderate high levels of hypercalcemia may produce fatigue or excessive tiredness. Heart rhythm abnormalities, increased urinary frequency, and kidney stones may also be present.

With higher levels of hypercalcemia, patients may experience muscle twitching, anxiety, depression, personality changes and confusion

Question 15

What are the reference ranges for creatinine?

Answer 15

60-110 micromol/L (0.7 - 1.2 mg/dL) men

45-90 micromol/L (0.5-1.0mg/dL) for women

Question 16

Discuss urea

Answer 16

Small nitrogenous compound, the main end product of protein catabolism in mammals, made in the liver from ammonia and bicarbonate and is one of the main components of urine

Decreased GFR = rise in blood urea nitrogen (BUN)

Question 17

Causes of hyperkalaemia

Answer 17

• Acute kidney injury
• Drugs: potassium sparing diuretics, ACE inhibitors, angiotensin 2 receptor blockers, spironolactone, ciclosporin, heparin
• Metabolic acidosis
• Addison’s disease
• Rhabdomyolysis
• Massive blood transfusion

*beta blockers interfere with K+ into cells and can cause hyperkalaemia in renal failure patients - beta agnoists can be used as emergency treatment