Disorders of Plasma Sodium Concentration
| Plasma sodium concentration (mmol/L) | Classification | Clinical features |
|---|---|---|
| >155 | Severe hypernatraemia | Delirium, reduced conscious level, coma |
| 150–155 | Moderate hypernatraemia | Muscle weakness, delirium |
| 143–150 | Mild hypernatraemia | Typically asymptomatic |
| 138–143 | Normal range | |
| 130–138 | Mild hyponatraemia | Typically asymptomatic |
| 125–130 | Moderate hyponatraemia | Headache, nausea, vomiting, muscle weakness, lethargy, delirium |
| <125 | Severe hyponatraemia | Delirium, ataxia, reduced conscious level, respiratory failure and seizures (reflecting cerebral oedema), especially when hyponatraemia has developed within 48 h. |