What this marker measures
Sodium is tightly regulated by the kidneys and hormones (ADH, aldosterone). The kidneys can adjust sodium excretion dramatically based on intake and fluid status. The normal range is narrow because small deviations can significantly affect brain and nerve function.
High or low: what it can mean
High Sodium
Elevated sodium (hypernatremia) usually indicates dehydration or loss of more water than sodium. This can occur with insufficient fluid intake, excessive sweating, or certain conditions affecting kidney water regulation.
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Low Sodium
Low sodium (hyponatremia) is the most common electrolyte abnormality. Causes include overhydration, diuretics, kidney or heart conditions, and certain hormonal disorders. Mild hyponatremia may be asymptomatic; severe cases can cause symptoms.
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Lifestyle considerations
- •Staying adequately hydrated (but not over-hydrated) is the key for most people
- •Athletes performing long-endurance events need to balance water and electrolyte intake carefully
Frequently asked questions
What is Sodium?
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Sodium is the primary electrolyte in blood and fluids outside cells. It regulates fluid balance, blood pressure, and nerve and muscle function.
What does Sodium measure?
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Sodium is tightly regulated by the kidneys and hormones (ADH, aldosterone). The kidneys can adjust sodium excretion dramatically based on intake and fluid status. The normal range is narrow because small deviations can significantly affect brain and nerve function.
What does high Sodium mean?
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Elevated sodium (hypernatremia) usually indicates dehydration or loss of more water than sodium. This can occur with insufficient fluid intake, excessive sweating, or certain conditions affecting kidney water regulation.
What does low Sodium mean?
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Low sodium (hyponatremia) is the most common electrolyte abnormality. Causes include overhydration, diuretics, kidney or heart conditions, and certain hormonal disorders. Mild hyponatremia may be asymptomatic; severe cases can cause symptoms.
What supports healthy Sodium levels?
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Staying adequately hydrated (but not over-hydrated) is the key for most people. Athletes performing long-endurance events need to balance water and electrolyte intake carefully
Related biomarkers
Editorial note
LabTestly explains lab markers using plain-English educational content. Reference ranges may vary by laboratory and should be interpreted with a clinician.
Educational content · Editorially reviewed for clarity · Last updated
Common sources used for lab-test education
Not medical advice
This page is for general understanding only and does not replace medical advice from your clinician. Reference ranges can vary by laboratory, age, sex, pregnancy status, medications, and clinical context.