What it is
In short Sodium helps control body water and nerve/muscle function. Hyponatremia means blood sodium is too low, often due to excess body water relative to sodium. In older adults, medicines and medical conditions are frequent drivers.
Why it matters: A rapid or very low level can affect the brain—causing confusion, falls, or seizures. Correcting it too fast is also dangerous. Care plans focus on cause and safe pacing.
When to call emergency
- Seizure, severe confusion, or fainting
- New trouble speaking, walking, or severe headache
- Persistent vomiting with weakness or drowsiness
These can signal severe/rapid sodium drop. Call your local emergency number immediately.
Typical symptoms
- Unsteadiness, falls, or dizziness
- Nausea, vomiting, poor appetite
- Headache, confusion, slowed thinking
- Muscle cramps, weakness
- Seizures (with severe cases)
Related topics
- Dizziness on Standing · Falls Prevention
- Chronic Kidney Disease (CKD) · Heart Failure (CHF)
- Medications & Side Effects
Why sodium drops (by volume status)
| Volume status | Common causes | Clues | Typical approaches |
|---|---|---|---|
| Hypovolemic (low body water & sodium) | Vomiting/diarrhea, diuretics (especially thiazides), bleeding, adrenal insufficiency | Dry mouth, low BP, elevated BUN/Cr ratio | Careful isotonic fluids, stop culprit meds; treat cause |
| Euvolemic (water gain without edema) | SIADH (lung/CNS disease, malignancy), SSRIs/SNRIs, carbamazepine, hypothyroidism, primary polydipsia, post-op | Normal exam; low serum uric acid; high urine sodium/osm | Fluid restriction, stop culprit meds, consider salt tablets/urea; treat cause |
| Hypervolemic (water & sodium gain, more water) | Heart failure, cirrhosis, nephrotic syndrome, advanced CKD | Edema, ascites, elevated JVP, weight gain | Fluid + sodium restriction, loop diuretics; optimize underlying condition |
How it’s diagnosed
Key labs & measures
- Repeat serum sodium to confirm
- Serum osmolality (true hypotonic vs. pseudo-hyponatremia)
- Urine osmolality & sodium to identify mechanism
- Thyroid (TSH), cortisol if suspected, kidney/liver panel
Treatment & safe correction limits
Emergent care
- Severe symptoms: consider hypertonic saline (3%) in monitored care
- Frequent sodium checks (every 2–4 hrs initially)
- Address seizures, airway, and the underlying cause
Safe correction
- Avoid over-correction to prevent osmotic demyelination
- Typical targets: ≤6–8 mEq/L rise in 24 hrs (clinician-directed)
- Desmopressin “brake” strategy may be used to control pace
Cause-directed steps
- Fluid restriction for SIADH/euvolemic states (amount individualized)
- Stop or adjust culprit meds (e.g., thiazides, SSRIs) after clinical review
- Loop diuretics for hypervolemic states; optimize heart/liver/kidney care
- Salt tablets, urea, or vasopressin antagonists in selected cases
Daily care & prevention
Medication review
- Ask about thiazide diuretics, SSRIs/SNRIs, carbamazepine, oxcarbazepine, desmopressin, and others that can lower sodium
- Never stop medicines on your own—request a supervised plan
Fluids: get a personalized target
- Restrictions vary (often 1–1.5 L/day in SIADH) and must fit heart/kidney status
- Track daily weights and symptoms (nausea, confusion, swelling)
Nutrition & salt
- Do not “chase” sodium with salty snacks unless advised—this may worsen fluid retention
- Prioritize balanced meals with adequate protein; consider oral nutrition support if appetite is poor
Quick answers
What sodium level is “low”?
Many labs flag <135 mEq/L as low. Risk depends on how low, how fast it fell, and your overall health.
Can drinking too much water cause it?
Yes—especially with SIADH or very low dietary solute intake. Follow fluid targets set by your clinician.
Is sports drink better than water?
Not necessarily. Some are high in sugar and may not address the cause. Ask your clinician what’s appropriate for you.
How fast should sodium be corrected?
Slowly and safely—often ≤6–8 mEq/L per 24 hours (clinician-directed) to avoid nerve damage from rapid shifts.
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