Electrolyte disturbance
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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
| Blood Level | Causes | Symptoms | Investigations | Treatment | |
| Hyponatraemia | <130mmol/l (<120mmol/L is severe) | Kidney: Addison's, renal failure; Water loss: D&V; Oedema: nephrotic syndrome, heart failure; SIADH | confusion, seizures, hypertension, cardiac failure, oedema, anorexia, nausea, weakness | U+E, urinary Na+ (>, urine osmolality | Fluid restriction, treat cause |
| 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. Alkalosis causing shift into cells. | At first, muscle weakness and pain from rhabdomylolysis, 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+ suggests secondary hyppoaldosteronism. | 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. Then calcium resonium. |
| Hypocalcaemia | <2.12mmol/L | Following thyroid/parathyroid surgery; with raised PO4-: chronic renal failure, hypoparathyroidism, pseudohypoparathyroidism; normal/low PO4-: osteomalacia, pancreatitis, overhydration, rhabdomyolysis; respiratory alkalosis | |||
| Hypercalcaemia | |||||
| 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. | Oral magnesium, or IV magnesium sulphate (MgSO4) |