Definition

A serum sodium test is a diagnostic procedure that measures the concentration of sodium in the serum. Sodium is an electrolyte, a mineral with an electrical charge, that plays a crucial role in maintaining proper fluid balance and regulating the acid-base equilibrium in the body. It is also essential for the optimal functioning of nerve and muscle cells.

Sodium primarily enters the body through daily food consumption. When sodium intake exceeds the body's needs, the kidneys regulate its levels by excreting excess sodium through urine, ensuring that the sodium concentration in the blood remains within a normal range. If sodium levels in the blood become abnormally high or low, it may indicate underlying health issues such as kidney disorders, dehydration, or other medical conditions.

Doctors often request a serum sodium test if a patient exhibits symptoms that suggest either an excess of sodium (hypernatremia) or a deficiency of sodium (hyponatremia). Symptoms indicating hypernatremia may include excessive thirst, loss of appetite, infrequent urination, nausea, vomiting, and diarrhea. Conversely, symptoms of hyponatremia may include weakness, nausea, vomiting, fatigue, headaches, seizures, muscle twitching, and altered mental status.

Serum sodium tests are commonly performed alongside other tests, such as serum potassium, serum chloride, and serum bicarbonate tests, as part of an electrolyte panel to evaluate the overall balance of electrolytes in the body.

Indication

This test is typically performed in the following situations:

• To assist in diagnosing sodium imbalances (hyponatremia or hypernatremia) when clinical signs or symptoms suggest such conditions.

• To monitor sodium levels in patients receiving treatment for certain illnesses or conditions.

• As part of routine screening during medical check-ups.

• To evaluate potential disorders affecting the heart, kidneys, or liver.

• To assess the balance of acid and base chemicals in the body.

Contraindication

There are no specific contraindications or conditions that prevent an individual from undergoing this test.

Preparation Before the Test

No special preparation is required before a serum sodium test. It can be conducted without the need for fasting. However, it is advisable to consult with a doctor beforehand, as certain medical conditions or medications may interfere with test results, leading to inaccurate measurements. Medications that can raise sodium levels in the blood include lithium and non-steroidal anti-inflammatory drugs (NSAIDs). Conversely, drugs that can lower serum sodium levels include diuretics, carbamazepine, and tricyclic antidepressants.

Test Procedure

The serum sodium test typically requires a serum sample of 0.25 - 0.5 ml. This sample is drawn from a vein and collected into a designated tube. Laboratory personnel will use personal protective equipment (PPE) such as gloves during the blood collection process.

Prior to drawing the blood, a tourniquet will be applied to the upper arm to make veins more visible, and the needle puncture site will be cleaned with antiseptic gauze. The blood is usually drawn from the crease of the elbow. Once the blood is collected into the tube, the tourniquet is removed, and pressure is applied to the puncture site, followed by cleaning with antiseptic gauze. This procedure takes only a few minutes.

The collected blood sample will then be analyzed using specialized equipment in the laboratory, and the results are typically available within a few hours.

Normal and Abnormal Values

Serum sodium levels are typically not distinguished based on age or gender. Below is the general range for normal and abnormal results from a serum sodium test.

However, it's important to note that each laboratory may have slightly different reference ranges due to variations in equipment or testing methods used. Therefore, the values in one laboratory might differ slightly from those in another.

Results and Recommendations (Follow-up Tests)

Low Sodium Levels

If your serum sodium test results show a low value, it is important to consult with a doctor. The doctor will likely recommend adjustments to your diet and lifestyle to promote better health. In some cases, medication or intravenous (IV) fluids may be prescribed to help restore blood sodium levels to normal.

Serum sodium levels below 120 mmol/L are generally considered dangerous and can lead to symptoms such as weakness, or in some cases, unilateral weakness. Levels ranging from 90 to 105 mmol/L are regarded as critical and can lead to more severe symptoms.

Conditions that can cause a decrease in blood sodium (known as hyponatremia) include gastrointestinal disorders, such as those causing nausea and vomiting, and kidney-related issues. Hyponatremia may also occur in conditions like metabolic acidosis (an imbalance of acids and bases in the body) and heart failure.

Even if your test results indicate low sodium levels, you should not attempt to diagnose the issue on your own. It is essential to seek professional medical advice from a doctor for further examination and diagnosis.

Normal Sodium Levels

If your serum sodium test results show a normal value, it generally indicates that your sodium levels are well-maintained and you are likely following a healthy lifestyle. It is important to continue this healthy routine to prevent any potential issues related to abnormal sodium levels, whether too high or too low.

High Sodium Levels

If your test results indicate high sodium levels, it is crucial to consult with a doctor. The doctor will likely recommend changes to your diet and lifestyle, and may also prescribe medication to help lower the sodium levels in your blood.

To manage high sodium levels, dietary changes and lifestyle adjustments are typically advised. These may include consuming a balanced diet, getting adequate rest, exercising for at least 15-30 minutes per day (3-5 times per week), avoiding alcohol consumption, and refraining from using over-the-counter medications without a doctor’s supervision.

Conditions that can cause high sodium levels in the blood (hypernatremia) include liver disease, heart failure, pregnancy, and burns.

Although your serum sodium levels may be elevated, self-diagnosis is not recommended. It is essential to consult a doctor for a thorough examination and to discuss any symptoms or concerns that you may have.

Consult the Right Doctor

Adults with abnormal serum sodium test results can seek guidance from a general practitioner. The general practitioner may recommend additional tests or initiate appropriate treatment based on the diagnosis. You may also be referred to a specialist, such as an internist or a kidney and hypertension consultant, for further discussion of your sodium levels. In pediatric patients, any abnormal test results should be discussed with a pediatrician for appropriate diagnosis and treatment.

Looking for more information about laboratory, radiology, and other examination results? Click here!