Hypernatremia

Serum sodium rising above 145 mEq/L and cellular dehydration.

Written by: Saygı Hospital Health Guide Editorial Board

Last updated: June 9, 2026

This content has been compiled by the Saygı Hospital Health Guide Editorial Board and is periodically reviewed by a specialist physician.

This content is for informational purposes only and does not constitute medical advice. You can book an appointment at our Dahiliye (İç Hastalıkları) department. Book Appointment →

What is Hypernatremia?

Hypernatremia is the rise of serum sodium level above 145 mEq/L and leads to cellular dehydration with the flow of water from intracellular fluid to the extracellular space. Shrinkage of central nervous system cells produces neurological symptoms.

The most common cause is pure water loss (insufficient fluid intake, excessive sweating, diabetes insipidus); less frequently, excessive sodium loading (hypertonic saline infusion, incorrect formula) is responsible. Bedridden elderly patients and infants form the highest risk group.

In treatment, since rapid correction can cause cerebral edema, sodium level should not be reduced by more than 10-12 mEq/L in 24 hours.

Symptoms

Excessive thirst (severe polydipsia)

Dry mucous membranes and mouth

Lethargy, drowsiness, and confusion

Muscle weakness and restlessness

Hyperreflexia and seizures

High fever and tachycardia

Coma in severe cases

Risk Factors

Elderly and care-dependent patients

Infants (insufficient breastfeeding)

Diabetes insipidus (central/nephrogenic)

High fever and sweating

Osmotic diuresis (hyperglycemia, mannitol)

Disorders of consciousness

Excessive salt intake

When to See a Doctor?

If you experience any of the following symptoms, seek medical attention promptly:

If there is lethargy and thirst in an elderly patient
When excessive urine output and excessive thirst are together
If altered consciousness and seizures occur (urgent)
If sufficient fluid cannot be taken in febrile illness
Suspicion of insufficient breastfeeding in an infant

Treatment Methods

Calculation and gradual correction of free water deficit

Plain water or hypotonic fluids orally if possible

IV 5% dextrose or 0.45% NaCl (slow infusion)

Desmopressin (DDAVP) in central DI

Thiazide diuretic and low-salt diet in nephrogenic DI

Correction rate: should not exceed 10-12 mEq/L in 24 hours

Which Department to Visit?

You can visit our Dahiliye (İç Hastalıkları) department for these complaints. Our specialist physicians will create the most suitable treatment plan for you.

Learn About Dahiliye (İç Hastalıkları) Department

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Health Disclaimer: The information on this page is prepared for general informational purposes only. It does not replace medical diagnosis and treatment. Please consult your physician for your complaints. Saygı Hospital does not accept responsibility for actions taken based on the information on this page.