Electrolyte Disorders Flashcards
Where is 65% of Na reabsorbed?
The proximal tubule.
Give 3 causes of hypernatremia.
Indaequate water intake. Impaired water retention. Skin - increased sweating. Lungs - hyperventilation.
Give 3 clinical symptoms of hypernatremia.
Thirst. Lethargy. Neurological dysfunction.
What characterizes hypernatraemia?
Sodium >145mmol/L.
What is the treatment for hypernatraemia?
Dextrose based IV fluid (low sodium). Oral solutions.
What characterizes hyponatraemia?
Sodium <135mmol/L.
What are the three types of hyponatraemia?
Hypovolaemic hyponatraemia. Euvolaemic hyponatraemia. Hypervolaemic hyponatraemia.
Give 2 causes of Hypovolaemic hyponatraemia.
GI losses. Renal losses.
Give 2 causes of Euvolaemic hyponatraemia.
Low dietary intake. Polydipsia. Syndrome of inappropiate Anti-diuretic hormone (SIADH).
Give 2 causes of Hypervolaemic hyponatraemia.
Heart failure. Cirrhosis.
Give 3 clinical manifestations of hyponatraemia.
Neurological symptoms e.g. lethargy, headache, confusion. Muscle symptoms e.g. cramps, weakness, fatigue. Gastrointestinal symptoms e.g. nausea, vomiting, abdominal cramps.
What is treatment for hyponatraemia?
Hypertonic saline (give it slowly so no overdose). If they have SIADH - fluid restriction.
Why do you give hypertonic saline slowly to to hyponatraemic patients?
Prevent overdose.
What characterizes a hyperkalaemic patient?
Serum potassium > 5.5mmol/L.
Give 3 causes of hyperkalaemia.
Increased intake. Redistribution - acidosis, beta- blockers. Decreased loss - renal failure, ACE inhibitors.
Give 2 clinical features of hyperkalaemia.
Muscle cramps. Arrhythmias.
Give 2 effects of hyperkalaemia on ECG.
Tall peaked T waves. Loss of p waves. Widened QRS complex.
What is the treatment for hyperkalaemia?
Calcium to stabilize myocardial cell membranes. Insulin with dextrose - increase potassium shift into cells. Loop diuretics - increase potassium excretion in kidneys.
Give 2 causes for hypokalaemia.
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.
Give 3 consequences of hypokalaemia.
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).
Give 2 effects of hypokalaemia on ECG.
Flattening of T waves. Depression of ST segment. Development of U wave.
What is the treatment for hypokalaemia?
Oral supplementation. IV potassium chloride. Potassium sparring diuretics.
What’s the difference between Euvolemic hyponatremia and Hypervolemic hyponatremia?
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.
