Hypernatraemia - this means a high sodium eg Na = 164 mmol/L
Hyponatraemia - this means a low sodium eg Na = 119 mmol/L
The reference range for serum sodium (Na) = 134 - 143 mmol/L
Remember that sodium and water go together, so...
Hypernatraemia usually due to not enough water rather than too much sodium
Hyponatraemia usually due to too much water rather than not enough sodium
