Sodium is an electrolyte that plays a crucial role in maintaining the balance of water in and around your cells. It also helps maintain stable blood pressure and is essential for proper nerve and muscle function.
When you look at a sodium blood test result, you are primarily looking at a measure of hydration. Abnormal sodium levels usually indicate a problem with how your body is handling water, rather than a problem with how much salt you are eating.
Typical Sodium reference ranges (mmol/L or mEq/L)
| Adults | 135 – 145 | Very tightly regulated by the kidneys |
|---|---|---|
| Critical Low | < 120 | Risk of neurological symptoms |
| Critical High | > 160 | Indicates severe dehydration |
Sodium levels must be kept in a tight range to prevent cells from swelling or shrinking dangerously.
What low sodium (Hyponatremia) means
Low sodium is called hyponatremia. It usually means you have too much water in your body relative to sodium, which dilutes the sodium concentration in your blood. This can happen from drinking extreme amounts of water, heart failure, liver cirrhosis, or kidney problems.
Certain medications, particularly diuretics (water pills) and some antidepressants, are common culprits. Mild hyponatremia might cause no symptoms, but moderate to severe cases can lead to headaches, confusion, nausea, lethargy, and in extreme cases, seizures.
What high sodium (Hypernatremia) means
High sodium is called hypernatremia. It almost always indicates dehydration — you have lost too much water, or you haven't consumed enough, making the sodium in your blood more concentrated. This is common in older adults who may lose their sense of thirst, or during severe bouts of vomiting, diarrhea, or sweating.
The primary symptom of hypernatremia is intense thirst. If the dehydration becomes severe, it can lead to confusion, muscle twitches, and lethargy.
When to contact your healthcare team
- Any result marked 'critical' requires immediate medical attention, as severe sodium imbalances can cause dangerous swelling or shrinking of brain cells.
- If a flagged sodium result is accompanied by confusion, extreme lethargy, or seizures, seek emergency medical care.
- If your sodium is mildly low and you recently started a new blood pressure or mood medication, bring it up at your next appointment.
Common questions
Does a high sodium blood test mean I eat too much salt?
Usually, no. Your kidneys are very good at filtering out excess dietary salt. A high sodium blood test almost always means you are dehydrated (lacking water), not that you ate too many salty foods.
Should I drink sports drinks to fix my sodium levels?
If your sodium is low because of a medical condition or medication, sports drinks won't fix it and might even add excess water that dilutes your sodium further. Always follow your doctor's specific advice for correcting an electrolyte imbalance.
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Medical disclaimer: Educational only; not medical advice, diagnosis, or treatment. AI-generated interpretations are not reviewed by a physician or human clinician. Do not use this content for emergencies; consult a qualified healthcare professional. Do not post personal laboratory results publicly. Reference intervals vary between laboratories—use the value, unit, date and range printed on your own report, and consult a qualified healthcare professional about your results and symptoms.