A nurse is assessing a client who has a sodium level of 116 meq/l

What is a sodium blood test?

A sodium blood test is a routine test that allows your doctor to see how much sodium is in your blood. It’s also called a serum sodium test. Sodium is an essential mineral to your body. It’s also referred to as Na+.

Sodium is particularly important for nerve and muscle function. Your body keeps sodium in balance through a variety of mechanisms. Sodium gets into your blood through food and drink. It leaves the blood through urine, stool, and sweat. Having the right amount of sodium is important for your health. Too much sodium can raise your blood pressure.

A lack of sodium can cause symptoms such as:

• nausea
• vomiting
• exhaustion
• dizziness

The sodium blood test is often part of a basic metabolic panel. This is a group of related tests. The basic metabolic panel includes tests for:

Blood sodium can also be part of an electrolyte panel. Electrolytes are substances that carry an electrical charge. Potassium and chloride are other electrolytes.

This test may be ordered if you have:

• eaten large amounts of salt
• not eaten enough or had enough water
• a serious illness, or gone through surgery
• received intravenous fluids

You may also receive this test to monitor medications that affect your sodium levels. These include diuretics and certain hormones.

This test is performed on a blood sample, obtained by venipuncture. A technician will insert a small needle into a vein on your arm or hand. This will be used to fill a test tube with blood.

You don’t need to prepare for this test. Consume a normal amount of food and water before going to the testing site. You may have to stop taking certain medications before this test. But, drugs should only be stopped on a doctor’s instruction.

When the blood is collected, you may feel some moderate pain or a mild pinching sensation. Any discomfort should only last a short time. After the needle is taken out, you may feel a throbbing sensation. You’ll be instructed to apply pressure to the puncture. A bandage will be applied.

There are few risks to taking a blood sample. Rare problems include:

If you bleed for a long period after your test, it may indicate a more serious condition. Excessive bleeding should be reported to your doctor.

Your doctor will go over your results with you. Results range from normal to abnormal.

Normal results

Normal results for this test are 135 to 145 mEq/L (milliequivalents per liter), according to the Mayo Clinic. But different laboratories use different values for “normal.”

Abnormally low levels

A blood sodium level lower than 135 mEq/L is called hyponatremia. Symptoms of hyponatremia include:

• fatigue
• nausea and vomiting
• headache
• loss of appetite
• confusion or disorientation
• hallucinations
• loss of consciousness or coma

Hyponatremia can cause damage to cells. It makes them swell up with too much water. This may be particularly dangerous in areas such as the brain.

Hyponatremia is more often a problem in older adults. It can be caused by:

• diuretics
• antidepressants
• certain pain medications
• large burns on the skin
• kidney disease
• liver disease or cirrhosis
• severe diarrhea or vomiting
• heart failure
• high levels of certain hormones, such as antidiuretic hormone or vasopressin
• drinking too much water
• not urinating enough
• excessive sweating
• ketones in the blood, known as ketonuria
• underactive thyroid, or hypothyroidism
• Addison’s disease, which is low hormone production in the adrenal gland

Abnormally high levels

Hypernatremia means high levels of sodium in the blood. It’s defined as levels that exceed 145 mEq/L. Symptoms of hypernatremia include:

• thirst
• fatigue
• swelling in hands and feet
• weakness
• insomnia
• rapid heartbeat
• coma

Hypernatremia is most often a problem in older adults, infants, and people who are bedridden. Causes of hypernatremia include:

• not drinking enough water
• drinking salty water
• eating too much salt
• excessive sweating
• diarrhea
• low levels of hormones such as vasopressin
• high levels of aldosterone
• Cushing’s syndrome, caused by excessive cortisol

Certain medications can also potentially cause hypernatremia. These include:

A blood sodium test is ordered by your doctor for a number of reasons. Sometimes it’s needed because you may be on certain medications that affect the sodium levels in your blood. Other times it may be part of a general health checkup. Either way it’s important to know how much sodium in your blood. Keeping it at the optimum level is good for your overall health.

Sodium is an electrolyte that plays an essential role in regulating levels of water and other substances in the body. When sodium levels in the blood become too low, it leads to hyponatremia, causing symptoms that include lethargy, confusion, and fatigue.

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Hyponatremia is the most common electrolyte disorder — research suggests that approximately 1.7% of people in the United States have the condition. It is more prevalent among people with cancer.

It can result from underlying conditions, such as kidney failure, or other factors, including drinking too much water or taking certain medications.

As the condition worsens, individuals may experience symptoms, such as:

• vomiting
• muscle twitches
• seizures

The definition of a low sodium level is below 135 milliequivalents per liter (meq/l). Severe hyponatremia occurs when levels drop below 125 meq/l. Health issues arising from extremely low sodium levels may be fatal.

Mild hyponatremia may not cause symptoms, but when they occur, they can include:

• confusion
• sluggishness
• a headache
• fatigue and low energy
• nausea
• restlessness
• irritability

If hyponatremia symptoms worsen, it may cause significant illness, disability, or in extreme cases, death.

Acute hyponatremia may also lead to serious brain swelling that can cause permanent disability or death.

If the condition worsens, it can cause severe symptoms, particularly in older adults. Severe symptoms may include:

• vomiting
• muscle weakness, spasms, and twitching
• lethargy
• disorientation

Doctors also associate mild chronic hyponatremia with the following complications:

• attention deficit
• gait instability
• osteoporosis
• fractures

Without adequate treatment, people with hyponatremia can develop:

• rhabdomyolysis, where the skeletal muscle tissues die
• altered mental status
• seizures
• a coma

Certain factors increase the risk of developing hyponatremia, including:

• older age
• having specific conditions, such as SIADH or kidney, heart, or liver disease
• taking certain diuretics, antidepressants, or pain medications
• taking ecstasy
• lifestyle factors, such as intense exercise, which may cause people to drink lots of water quickly

People at risk of hyponatremia or who develop symptoms should consult their doctor immediately, as they may need urgent medical treatment.

Individuals with symptoms, including vomiting, seizures, or loss of consciousness, require immediate attention. They should call an ambulance or go to the nearest emergency room.

To diagnose low sodium levels, a doctor will take a medical history, perform a physical examination, and order a blood test.

If the blood screening indicates low sodium levels, a healthcare professional will typically need to perform additional tests to determine the cause.

Treatment for hyponatremia involves restoring sodium levels and addressing what has caused them.

Restoring blood sodium levels

Those with mild-to-moderate hyponatremia due to lifestyle factors or medication could increase their sodium to usual levels by drinking less and adjusting or switching their medications.

Individuals with severe symptoms often require hospitalization and an intravenous sodium treatment to get their sodium levels back to usual. They may also require drugs to treat seizures or other hyponatremia symptoms.

Treating the underlying cause

Often, the cause of hyponatremia is an underlying condition, which will usually require specific treatment.

For example, if a person has liver disease, kidney disease, or heart disease, these can be potential causes of hyponatremia. These conditions may require treatment with medications or surgery.

People with a thyroid disorder can typically manage their symptoms and prevent hyponatremia and other complications with medications. They may also need to make certain lifestyle changes, such as avoiding smoking and reducing alcohol consumption.

SIADH usually requires ongoing treatment to prevent hyponatremia. Individuals with the condition may need to restrict their intake of fluids and take salt tablets and other medications.

To avoid low blood sodium levels, a person should:

• avoid drinking excessive amounts of water
• consume sports drinks during intense exercise
• avoid taking ecstasy
• seek treatment for medical conditions
• discuss medications with a doctor
• seek medical care if vomiting or diarrhea symptoms persist

The outlook for people with low sodium levels depends on the severity of the condition and the underlying cause.

Acute hyponatremia, which develops quickly, is more severe than chronic cases, which have a longer onset time. In severe cases, the condition can be fatal.

To improve their outlook, people should be aware of the symptoms of hyponatremia and seek prompt medical attention if they experience them. Those at risk of low sodium levels should be especially vigilant.