Electrolyte Disorders

Question 1

Where is 65% of Na reabsorbed?

Answer 1

The proximal tubule.

Question 2

Give 3 causes of hypernatremia.

Answer 2

Indaequate water intake. Impaired water retention. Skin - increased sweating. Lungs - hyperventilation.

Question 3

Give 3 clinical symptoms of hypernatremia.

Answer 3

Thirst. Lethargy. Neurological dysfunction.

Question 4

What characterizes hypernatraemia?

Answer 4

Sodium >145mmol/L.

Question 5

What is the treatment for hypernatraemia?

Answer 5

Dextrose based IV fluid (low sodium). Oral solutions.

Question 6

What characterizes hyponatraemia?

Answer 6

Sodium <135mmol/L.

Question 7

What are the three types of hyponatraemia?

Answer 7

Hypovolaemic hyponatraemia. Euvolaemic hyponatraemia. Hypervolaemic hyponatraemia.

Question 8

Give 2 causes of Hypovolaemic hyponatraemia.

Answer 8

GI losses. Renal losses.

Question 9

Give 2 causes of Euvolaemic hyponatraemia.

Answer 9

Low dietary intake. Polydipsia. Syndrome of inappropiate Anti-diuretic hormone (SIADH).

Question 10

Give 2 causes of Hypervolaemic hyponatraemia.

Answer 10

Heart failure. Cirrhosis.

Question 11

Give 3 clinical manifestations of hyponatraemia.

Answer 11

Neurological symptoms e.g. lethargy, headache, confusion. Muscle symptoms e.g. cramps, weakness, fatigue. Gastrointestinal symptoms e.g. nausea, vomiting, abdominal cramps.

Question 12

What is treatment for hyponatraemia?

Answer 12

Hypertonic saline (give it slowly so no overdose). If they have SIADH - fluid restriction.

Question 13

Why do you give hypertonic saline slowly to to hyponatraemic patients?

Answer 13

Prevent overdose.

Question 14

What characterizes a hyperkalaemic patient?

Answer 14

Serum potassium > 5.5mmol/L.

Question 15

Give 3 causes of hyperkalaemia.

Answer 15

Increased intake. Redistribution - acidosis, beta- blockers. Decreased loss - renal failure, ACE inhibitors.

Question 16

Give 2 clinical features of hyperkalaemia.

Answer 16

Muscle cramps. Arrhythmias.

Question 17

Give 2 effects of hyperkalaemia on ECG.

Answer 17

Tall peaked T waves. Loss of p waves. Widened QRS complex.

Question 18

What is the treatment for hyperkalaemia?

Answer 18

Calcium to stabilize myocardial cell membranes. Insulin with dextrose - increase potassium shift into cells. Loop diuretics - increase potassium excretion in kidneys.

Question 19

Give 2 causes for hypokalaemia.

Answer 19

Reduced intake. Increased excretion e.g. GI losses - diarrhoea, renal losses - diuretics. Insulin gets potassium into the cell. Ketoacidosis - hydrogen ions replace potassium ions which is lost in urine.

Question 20

Give 3 consequences of hypokalaemia.

Answer 20

Cardiac arrhythmias. Neuromuscular effects e.g. paralysis. Renal effects e.g. metabolic acidosis (as potassium uptake into cells exchanged for hydrogen ions), polyuria (due to decreased responsiveness to ADH).

Question 21

Give 2 effects of hypokalaemia on ECG.

Answer 21

Flattening of T waves. Depression of ST segment. Development of U wave.

Question 22

What is the treatment for hypokalaemia?

Answer 22

Oral supplementation. IV potassium chloride. Potassium sparring diuretics.

Question 23

What’s the difference between Euvolemic hyponatremia and Hypervolemic hyponatremia?

Answer 23

Euvolemic hyponatremia: normal body sodium with increase in total body water. Hypervolemic hyponatremia: increase in total body sodium with greater increase in total body water.