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Sodium Test

⚠️ Update approaching🔬 Evidence: ModerateInternal Medicine
Diğer adları: Na, Serum sodium, Sodium level
⚠️

Discuss your test results with your doctor. This page is for informational purposes only and does not provide a diagnosis.

⚡ Key Facts

• Serum sodium reflects the body's water balance — it does not directly measure salt intake • Normal: 136–145 mmol/L • Low sodium (hyponatremia) is one of the most common electrolyte disorders • Critical imbalances may require urgent evaluation

🧪 What Does This Test Measure?

The sodium test measures the concentration of sodium in the blood, the primary electrolyte responsible for maintaining fluid balance and blood pressure.

📋 Why Is It Ordered?

Ordered for fluid-electrolyte balance evaluation, kidney/heart/liver disease monitoring, and medication side effect assessment.

🔧 Preparation

No special preparation is generally required. Measured as part of routine blood panels.

📊 Reference Ranges

Normal: 136–145 mmol/L Hyponatremia: <135 mmol/L Hypernatremia: >145 mmol/L ⚠️ Reference ranges may vary slightly by laboratory.

⬆️ High Values

High sodium (hypernatremia) is usually associated with water loss or insufficient water intake rather than excess salt consumption.

⬇️ Low Values

Low sodium (hyponatremia) is most commonly associated with excess body water. Certain medications, heart failure, and hormonal conditions may contribute.

⚙️ What Can Affect Results?

Fluid intake, medications, kidney function, hormonal conditions, and age may affect sodium results.

🔬 Evidence Summary

Moderate evidence: 2 guidelines and 4 comprehensive reviews.

📚 Most Important Studies on This Topic

1

Clinical practice guideline on diagnosis and treatment of hyponatraemia

Guideline· European Journal of Endocrinology / Nephrology Dialysis Transplantation · 2014 · PMID: 24569496

2

Disorders of Plasma Sodium — Causes, Consequences, and Correction

Review· New England Journal of Medicine · 2015 · PMID: 25551526

3

Hyponatremia

Review· New England Journal of Medicine · 2000 · PMID: 10824078

✅ Key Takeaways

💡

What you learned: Serum sodium reflects water balance rather than salt intake. Both high and low values require clinical evaluation.

⛔

A sodium result alone cannot determine the cause of imbalance. Clinical context, other tests, and fluid assessment are needed.

🔬 Sources Used on This Page

6 sources · Most recent publication: 2023
📋
Guideline
Expert society and guideline recommendations
2
sources
📖
Review
Comprehensive topic evaluation
4
sources
Overall assessment: Evidence level for this topic is moderate. This page is supported by 2 guidelines, 4 reviews.

📝 Questions to Ask Your Doctor

Be prepared for your appointment. Add questions to your list.

📋 References

[PMID: 37851876] The Syndrome of Inappropriate Antidiuresis. New England Journal of Medicine, 2023.
[PMID: 25551526] Disorders of Plasma Sodium — Causes, Consequences, and Correction. New England Journal of Medicine, 2015.
[PMID: 24569496] Clinical practice guideline on diagnosis and treatment of hyponatraemia. European Journal of Endocrinology / Nephrology Dialysis Transplantation, 2014.
[PMID: 24074529] Diagnosis, evaluation, and treatment of hyponatremia: expert panel recommendations. American Journal of Medicine, 2013.
[PMID: 10824078] Hyponatremia. New England Journal of Medicine, 2000.
[PMID: 10816188] Hypernatremia. New England Journal of Medicine, 2000.
Last reviewed: 4/1/2026
Next review: 4/1/2027

🔗 Related Topics

🧪 Potasyum (K)🧪 Klor (Cl)🧪 Creatinine🧪 eGFR
⚖️ This page does not replace medical advice. Make treatment decisions with your doctor.
Content is based on scientific studies indexed in PubMed and current clinical guidelines.