🩺 General MedicineMetabolicStudentInternResident

Hypernatraemia

Also known as: high sodium · hypernatremia

A raised serum sodium — almost always a water problem (water deficit relative to sodium). Thirst and lethargy progress to irritability, seizures and coma. Correct SLOWLY to avoid cerebral oedema.

Source · Reviewed 2026-08-15 · v1.0— AI-assisted draft — verify against the cited guideline before clinical use.

⚕️ Education only — not medical advice. Verify against the latest official guideline and your local protocol; confirm every drug dose against the cited source before clinical use.

Who gets it

The very young, the elderly and the unconscious (no access to water), diarrhoea/vomiting, fever/heat, osmotic diuresis (hyperglycaemia) and diabetes insipidus.

Red flags — escalate / refer

Altered mental state, seizures, marked volume depletion/shock, or a very high sodium → emergency with careful correction.

Work-up / diagnosis

1Assess volume status; measure serum and urine sodium and osmolality to classify the cause and check the renal response.
2Check glucose and renal function; suspect diabetes insipidus if the urine is dilute despite a high serum sodium.

Management — overview

Restore water — orally where possible, otherwise IV.
Correct shock with isotonic fluid FIRST, then replace the free-water deficit gradually.
Lower the sodium slowly (avoid overly rapid correction → cerebral oedema); treat the cause (stop losses; desmopressin for central diabetes insipidus).

In-depthFull dosing & advanced protocol

Drug dosing

Water / IV fluids (free-water replacement)

Correct the water deficit gradually

Adult dose: Calculated free-water deficit replaced slowly per protocol
Route: Oral / IV

Caution: Resuscitate hypovolaemia with isotonic fluid before free water; do not lower sodium too fast.

ICMRStandard Treatment Workflows (STWs), India — Dept. of Health Research & ICMR (2022+) ↗

Desmopressin

Central diabetes insipidus

Adult dose: Per protocol
Route: Intranasal / oral / parenteral

WHOWHO Model List of Essential Medicines (electronic EML) (2025 (24th)) ↗

Slow correction; urine osmolality guides the cause

Overly rapid correction of chronic hypernatraemia risks cerebral oedema — respect the recommended maximum fall per 24 hours.
Give isotonic fluid to restore circulation before free-water replacement in the shocked patient.
Urine osmolality distinguishes renal from extrarenal water loss and points to diabetes insipidus.

ICMRStandard Treatment Workflows (STWs), India — Dept. of Health Research & ICMR (2022+) ↗

References

Guidelines change. If something here is out of date, tell us — we keep these current.

🚩 Report outdated / suggest update

More protocols

HypertensionPersistently raised arterial pressure (≥140/90 mmHg) — a leading, modifiable cause of stroke, heart attack, heart failure and kidney disease.DengueAn Aedes-borne viral febrile illness. Most cases self-limit, but plasma leakage can cause severe dengue — early recognition of warning signs and careful fluid therapy save lives.MalariaA mosquito-borne protozoal (Plasmodium) febrile illness. In India P. vivax and P. falciparum predominate; prompt diagnosis and species-specific treatment prevent severe disease.

Loading…

👤 Who gets it

🚩 Red flags — escalate / refer

🔎 Work-up / diagnosis

🧭 Management — overview

💊 Drug dosing

Water / IV fluids (free-water replacement)

Desmopressin

📈 Slow correction; urine osmolality guides the cause

📚 References

More protocols

👤 Who gets it

🚩 Red flags — escalate / refer

🔎 Work-up / diagnosis

🧭 Management — overview

💊 Drug dosing

Water / IV fluids (free-water replacement)

Desmopressin

📈 Slow correction; urine osmolality guides the cause

📚 References

More protocols

Who gets it

Red flags — escalate / refer

Work-up / diagnosis

Management — overview

Drug dosing

Slow correction; urine osmolality guides the cause

References

Who gets it

Red flags — escalate / refer

Work-up / diagnosis

Management — overview

Drug dosing

Slow correction; urine osmolality guides the cause

References