Sodium: Key Functions, Levels, and Health Impact

What Is Sodium?

Sodium is an important electrolyte that helps control fluid balance, blood pressure, and proper nerve and muscle function. In medicine, sodium is crucial for assessing a person's hydration status, kidney function, and cardiovascular health.

When there’s too much or too little sodium in the body, it can disrupt these critical functions. For instance, low sodium levels, a condition known as hyponatremia, can lead to confusion, fatigue, and even life-threatening symptoms in severe cases. 

On the other hand, high sodium levels, or hypernatremia, can result in high blood pressure and kidney damage. This makes sodium a key biomarker in evaluating several health issues.

When Is Sodium Testing Recommended?

Sodium testing is often part of routine health checkups and diagnostic tests. It helps identify potential imbalances and track overall health. 

A healthcare provider may recommend a sodium test under various conditions, including:

• As part of a general electrolyte panel in routine blood tests
• To evaluate dehydration or fluid imbalance
• To diagnose kidney disease or monitor kidney function
• If symptoms of hyponatremia (low sodium) such as confusion, fatigue, or nausea are present
• If there are signs of hypernatremia (high sodium), such as increased thirst or muscle weakness
• To investigate dermatological or hair-related issues that may suggest electrolyte imbalance

How Is Sodium Testing Conducted?

Sodium levels can be tested using blood, urine, hair, or even nails. 

The most common way is through a serum sodium test, which is a part of broader panels like the Complete Metabolic Panel (CMP) or Basic Metabolic Panel (BMP). These panels provide a more comprehensive look at the body’s electrolyte and kidney function.

• Blood Test: The most common way to check sodium levels, typically requiring 12 hours of fasting.
• Urine Test: This may be done to assess kidney function or sodium retention. It requires patients to avoid diuretics for two days before the test (consult with a doctor first).
• Hair or Nail Test: These tests measure long-term sodium accumulation (about 5-8 weeks) and require no special preparation, though hair coloring or perming should be avoided before the test.

Sodium levels in blood and urine are measured through electrolyte analysis, while atomic absorption spectrometry (AAS) is used for hair and nails.

What Are the Normal Sodium Levels?

For adults, normal sodium levels in the blood typically range from 135 to 145 mmol/L. Maintaining levels within this range is crucial for bodily functions.

Note: The exact normal range and units of measurement may differ slightly depending on the laboratory and the specific testing methods used.

What Do Abnormal Sodium Levels Mean?

Sodium High Levels

When sodium levels are above the normal range (hypernatremia), it often indicates dehydration or an imbalance in water and sodium intake. Here are common causes of elevated sodium levels:

• Cushing's syndrome: A condition where the body produces excess cortisol, leading to sodium retention.
• Kidney disease: Issues with the kidneys can impair sodium regulation.
• Hyperaldosteronism: Excess aldosterone can cause the body to retain sodium and excrete potassium.
• Diabetes mellitus: In some cases, diabetes can contribute to electrolyte imbalances, including elevated sodium.
• Bartter's syndrome: This rare genetic disorder affects how the kidneys handle salt.

• Work with your healthcare provider to identify the cause of high sodium.
• Stay hydrated by drinking sufficient water, especially in hot climates or after physical activity.
• Limit salt intake in your diet. Opt for fresh foods and avoid processed items high in sodium.
• Monitor and manage any underlying conditions that may be contributing to sodium imbalance.

Sodium Low Levels

When sodium levels fall below the normal range (hyponatremia), the body’s water and electrolyte balance is disrupted, often leading to symptoms like weakness, nausea, and confusion. Causes of low sodium levels include:

• Hypothyroidism: Reduced thyroid function can lower sodium levels.
• Fluid loss: Excessive sweating, vomiting, or diarrhea can lead to a significant loss of sodium.
• Malabsorption: Conditions like celiac disease can affect nutrient absorption, including sodium.
• Heart failure: Fluid buildup from heart failure can dilute sodium levels in the blood.
• Severe vomiting and diarrhea: These can cause rapid loss of sodium, leading to dehydration and low sodium levels.

• Consult your doctor to identify the root cause of low sodium.
• Drink water in moderation. Overhydration can further dilute sodium levels.
• Avoid excessive alcohol consumption, as it can affect the body’s electrolyte balance.
• Eat protein-rich foods to help maintain muscle mass and proper electrolyte levels.
• Ensure your diet contains a balanced amount of salt to avoid further sodium depletion.

Which Specialist Should You Consult?

If you have abnormal sodium levels, it’s important to consult the appropriate healthcare professional based on your symptoms:

• General Physician: For overall health assessments and guidance.
• Nephrologist: If the issue relates to kidney function.
• Cardiologist: For sodium-related concerns tied to cardiovascular health.
• Neurologist: If low sodium levels are affecting neurological function.
• Dermatologist: If skin or hair symptoms are present due to sodium imbalances.