Electrolyte disturbance

Important disturbances

The big uns are:

• Hyponatraemia & Hypernatraemia
• Hypokalaemia & Hyperkalaemia
• Hypocalcaemia & Hypercalcaemia
• Hypomagnesaemia

They mostly have their own pages, just click on them, or for a condensed version, see below.

The Table of Disturbance

	Causes	Symptoms	Investigations	Treatment
Hyponatraemia <135mmol/l (<120mmol/L is severe)	Kidney: Addison's, renal failure, diuretics; Water loss: D&V; Oedema: nephrotic syndrome, heart failure; SIADH	confusion, seizures, hypertension, cardiac failure, oedema, anorexia, nausea, weakness	U+E, urinary Na+>20mmol/L, urine osmolality	Treat cause. Hypovolaemia: isotonic saline relacement. Normovolaemic: fluid restriction. Hypervolaemia: furosemide, ACE inhibitor, fluid restriction
Hypernatraemia >145mmol/L	Not enough water: poor intake, diuretics, diabetes insipidus.	thirst, confusion, coma, seizures + signs of dehydration	U+E raised urea and albumin	Water orally or 5% dextrose iv (4L/24h). Can use 0.9% saline - do not use hypotonic solutions
Hypokalaemia <3.5 mmol/l	Loss: thiazide and loop diuretics, Cushing's, D&V, poor dietary intake, alkalosis causing shift into cells.	At first, muscle weakness, pain from rhabdomylolysis, tetany, arrhythmias and constipation. Later paralysis and paraesthaesia.	Urinary potassium - low suggests poor intake, shift into the intracellular space or GI loss. Where high, suggests renal loss. Urinary sodium - low Na+; high K+ in wee suggests secondary hyperaldosteronism. Prolonged QT.	Oral Potassium, or IV KCl of 40 mmol/l, no faster than 20 mmol/hr, or their heart stops.
Hyperkalaemia >5.5 mmol/l	Renal: decreased excretion or drugs. Rhabdomyolisis. Acidosis, causing K+ to swap with H+. Potassium sparing diuretics.	First nothing. Then weakness and paralysis, then heart arrhythmias. Then shortness of breath. Then death.	Blood and ABG K+. ECG, looking for tented T waves, prolonged PR and absent P waves.	Stop potassium intake/sparing. Calcium gluconate, plus insulin and glucose. Nebulised salbutamol. Then calcium resonium.
Hypocalcaemia <2.12mmol/L	Para/thyroid surgery; PO4-↑: chronic renal failure, hypoparathyroidism, pseudohypo...; PO4-↓↔: osteomalacia, pancreatitis, overhydration, rhabdomyolysis; respiratory alkalosis	tetany, depression, perioral paraesthesia, carpo-pedal spasm (esp. with BP measuring), neuromuscular excitability (tap facical nerve, muscles twitch), cataract chronically	ECG: prolonged Q-T interval	Mild: Ca2+ 5mmol. Severe: calcium gluconate 10mL 10%ivi 30min, repeat.
Hypercalcaemia 2.65 mmol/l	Hyperparathyroidism, or cancer. And Lithium use. Pretty much it.	Confusion, constipation, polyuria, nausea. Chronic causes stones.	U+Es for serum calcium. And magnesium, albumin, phosphate and creatinine. ECG: prolonged Q-T	Fluids. Furosemide. Pamidronate (a bisphosphonate).
Hypomagnesaemia <0.7 mmol/l	Diuretics, Alcohol abuse, D&V, Malnutrition, Aminoglycosides (gentamicin, tobramycin) and Post MI.	Arrhythmias, Tetany, Irritability	Blood test. 40% will have hypocalcaemia and 60% will have hypokalaemia. ECG will show a prolonged QT and/or Torsades	Oral magnesium, or IV magnesium sulphate (MgSO4)