The following symptoms and complaints may indicate hyponatremia (sodium deficiency):
- Edema (water retention) [hyponatremia in hypervolemia, e.g., heart failure (cardiac insufficiency), liver cirrhosis (irreversible damage to the liver leading to gradual connective tissue remodeling of the liver with impairment of liver function), nephrotic syndrome]
- Moderately severe symptoms:
- Severe symptoms:
- Vomiting
- Cardiorespiratory problems
- Vertigo (dizziness)
- Muscle cramps
- Epilepsy (seizures)
- Impaired consciousness (lethargy/sleepiness, somnolence/drowsiness with abnormal sleepiness to coma/severe deep unconsciousness characterized by lack of response to address)
The occurrence of cerebral symptoms in this case depends on the extent of hyponatremia and its development over time. In slowly developing hyponatremia, cerebral symptoms do not occur until the serum sodium concentration is < 115 mmol/l. In contrast, cerebral edema (brain swelling) in acute hyponatremia occurs at serum concentrations < 125 mmol/l.
Further notes
- Patients with chronic hyponatremia are conspicuous for gait unsteadiness (gait disorder) and cognitive deficits.
- Hyponatremia is considered an independent risk factor for increased mortality (death rate) from cardiovascular and pulmonary disease.
- Hyponatremia is one of the predictors of the Hospital Score (see below), which predicts the risk of readmission of patients in the first 30 days after hospital discharge.
Hospital Score
| Predictors | Score |
| Hemoglobin level < 12 g /dl (H) | 1 |
| Discharge from oncology (O) | 2 |
| Hyponatremia (< 135 mmol/l) (S for eng. “sodium“). | 1 |
| Intervention (P for “Procedure”) | 1 |
| Emergency entry (IT for “index type urgent”) | 1 |
| Number of hospitalizations (A for “Admissions”) in the last year. | |
| – – 0-1 | 0 |
| – – 2-5 | 2 |
| – – >5 | 5 |
| Stay ≥ 5 days (L for “Length”). | 2 |
Legend
- 0-4 points: low risk of re-hospitalization; avoidable readmission 5.8%.
- 5-6 points: intermediate risk; avoidable readmission 11.9%.
- 7-13 points: high risk; avoidable readmission 22.8%.