Understanding Lab Tests for Hyponatremia
Written by Private MD Labs Medical Writing Team • Last Updated: September 8, 2025
Hyponatremia is a medical condition characterized by abnormally low levels of sodium in the blood. This electrolyte imbalance can be caused by various factors including excessive fluid intake, certain medications, heart failure, kidney disease, or dehydration. Blood tests are essential for diagnosing hyponatremia and determining its underlying cause.
Top Recommended Test
Electrolyte Panel
This focused panel directly measures sodium levels along with other key electrolytes. It's the most direct test for diagnosing hyponatremia and monitoring treatment response. The test can help determine if low sodium levels are due to excessive fluid intake, certain medications, heart failure, or kidney disease.
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Why Blood Testing is Essential for Hyponatremia
Since hyponatremia involves abnormal sodium levels in the blood, specific blood tests are the primary diagnostic tools. These tests not only confirm the diagnosis but also help healthcare providers identify the underlying cause and monitor treatment effectiveness. Electrolyte panels and comprehensive metabolic profiles can directly measure sodium levels and assess related organ function.
Other Relevant Tests
Comprehensive Metabolic Profile (includes eGFR)
This comprehensive test measures sodium levels along with other important metabolites and kidney function markers. Since hyponatremia can be caused by kidney problems, heart conditions, certain medications, or dehydration, this panel provides a complete picture of your body's metabolic status and helps identify underlying causes.
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Kidney Function Profile
This specialized panel focuses on kidney function, which is crucial since kidney disease is a common cause of hyponatremia. The test helps determine if kidney dysfunction is contributing to the low sodium levels and can guide appropriate treatment decisions.
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Post COVID-19 Expanded Panel
This comprehensive panel includes sodium measurement and is particularly valuable for individuals who have had COVID-19, as the infection can sometimes lead to electrolyte imbalances including hyponatremia. It helps assess overall recovery and identifies any lingering metabolic effects.
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Anion Gap Panel (Electrolyte Balance)
This test specifically measures electrolyte balance including sodium levels. It's essential for diagnosing hyponatremia and understanding the relationship between different electrolytes in your blood, helping to identify whether the condition is related to kidney disease, heart failure, or excessive water intake.
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Understanding Your Results
Normal sodium levels typically range from 135-145 milliequivalents per liter (mEq/L). Hyponatremia is generally diagnosed when sodium levels fall below 135 mEq/L. The severity of symptoms often correlates with how low the sodium level is and how quickly it developed. Your healthcare provider will interpret your results in the context of your symptoms and medical history.
Important Considerations
The information here is for educational purposes only and is not a substitute for professional medical advice. Hyponatremia can be a serious condition requiring prompt medical attention. Always consult with a healthcare provider for proper diagnosis, treatment, and monitoring of this condition.
