Low Sodium (Hyponatremia) Treatment Methods

Low sodium (hyponatremia) is an electrolyte abnormality that can cause serious health problems. Please continue reading to learn more about the causes, symptoms, and treatments for low blood sodium.

What is the role of sodium in the body?

Most of the sodium in the body is present in the blood and the extracellular fluid that surrounds cells. Sodium plays a vital role in maintaining fluid balance in the body. It is also important for nerve and muscle function.

You obtain sodium from your diet (foods and drinks), and it is removed from your body through sweat and urine. The amount of sodium in your body affects the volume of blood and extracellular fluid.

In healthy individuals, the body continuously monitors blood volume, extracellular fluid volume, and sodium concentration and maintains sodium homeostasis (balance) by adjusting the amount of urine sodium excretion. When there is a problem with this balancing mechanism, it can result in hypernatremia (high serum sodium) or hyponatremia (low serum sodium).

What is a safe sodium level in the body?

A safe sodium level in the body is 135 to 145 milliequivalents per liter (mEq/L) or millimoles/L (mmol/L). Hyponatremia refers to a serum sodium level below 135 mEq/L. Hypernatremia (high sodium concentration in the blood) refers to a value above 145 mEq/L.

What is the main cause of low sodium?

Common causes of hyponatremia include taking medications such as diuretics (water pills), fluid loss due to diarrhea or vomiting, heart failure, liver disease, and kidney disease.

A condition called the syndrome of inappropriate antidiuretic hormone secretion (SIADH) can also cause hyponatremia. In people with SIADH, there is an excess of antidiuretic hormone (ADH) (also called vasopressin). This hormone plays a role in fluid and sodium balance. People with SIADH retain water instead of excreting it in their urine.

Causes of hyponatremia (low sodium) can be classified according to the blood volume status:

Hypovolemic hyponatremia (low blood volume and low sodium):

Fluid loss due to severe diarrhea or vomiting
Diuretic-induced hyponatremia or thiazide-induced hyponatremia in people taking thiazide diuretics or loop diuretics (these medications cause increased renal water excretion)
Osmotic diuresis (increased urination due to the presence of certain substances in the urine, for example, in people with severe hyperglycemia or very high blood sugar levels)
Medical conditions such as adrenal insufficiency and mineralocorticoid deficiency
Salt-losing nephropathies (kidney conditions such as interstitial nephritis and medullary cystic disease)

Euvolemic hyponatremia (low sodium without volume depletion or volume overload)

Excessive fluid intake (drinking too much water)
Stress-induced and postoperative hyponatremia
Medical conditions such as Addison disease, hypothyroidism, and the syndrome of inappropriate antidiuretic hormone secretion (SIADH)
Certain medications such as diabetes medications (tolbutamide, chlorpropamide), opioids, anti-seizure medications (carbamazepine, barbiturates), cholesterol-lowering medications (clofibrate), and chemotherapy drugs (vincristine)

Hypervolemic hyponatremia (increased blood volume and low sodium)

Congestive heart failure
Liver cirrhosis
Nephrotic syndrome or chronic kidney disease
Use of recreational drugs like ecstasy (MDMA)

What is acute hyponatremia and chronic hyponatremia?

Acute hyponatremia is when serum sodium levels fall rapidly. In such cases, the hyponatremia has been present for less than 48 hours. Acute hyponatremia can result in serious health complications such as cerebral edema (swelling in the brain), coma, and even death.

Chronic hyponatremia is when serum sodium levels fall more gradually (over a period of 48 hours or more). The complications of chronic hyponatremia tend to be less severe.

What happens when serum sodium concentration falls?

When serum sodium falls, you can develop hyponatremia symptoms such as nausea, vomiting, headache, drowsiness, dizziness, low energy, tiredness, neurologic symptoms (forgetfulness, confusion, irritability, restlessness), muscle cramps, muscle weakness, seizures, and coma. It is worth noting that many people with mild hyponatremia are asymptomatic.

What are the risks of severe hyponatremia?

Severe hyponatremia can result in serious and life-threatening complications, including cerebral edema (brain swelling), brain herniation, respiratory arrest, seizures, and coma.

How is hyponatremia diagnosed?

Healthcare providers can diagnose hyponatremia (low sodium) with a blood test to measure serum sodium levels. Other tests may be done to identify the cause of the hyponatremia, including blood urea nitrogen, potassium, magnesium, calcium, phosphate, urine sodium concentration, serum osmolality, and urine osmolality.

How is low sodium (hyponatremia) treated?

Low sodium (hyponatremia) is treated with hypertonic saline (3 percent saline). However, asymptomatic patients with mild hyponatremia may not require hypertonic saline treatment and may simply be observed.

The key to the management of low sodium (hyponatremia) is to find out the cause and remove it if possible, for example, by discontinuing a medication that has caused low sodium or advising fluid restriction if hyponatremia is from drinking too much water.

The treatment plan for hospitalized patients depends on many factors. Healthcare providers take into account mild symptoms versus severe symptoms, and in symptomatic patients, the severity of the symptomatic hyponatremia:

Mild hyponatremia is serum sodium concentrations between 130 and 134 mEq/L
Moderate hyponatremia is serum sodium concentrations between 120 and 129 mEq/L
Severe hyponatremia is serum sodium levels below 120 mEq/L

Acute or symptomatic hyponatremia requires emergency treatment because there is a high risk of complications such as cerebral edema (brain swelling), herniation, and seizures. Therefore, acute hyponatremia requires aggressive therapy with hypertonic saline infusion to increase serum sodium levels by 4 to 6 mEq/L over a few hours.

On the other hand, if it is chronic hyponatremia with a very low serum sodium concentration, the correction needs to be done at a slower rate. Overly aggressive therapy and rapid correction of chronic severe hyponatremia can lead to a potentially fatal condition called osmotic demyelination syndrome (ODS), in which there is destruction of the protective myelin sheath that covers brain cells.

The goal of low sodium (hyponatremia) treatment is to prevent a further drop in serum sodium levels, relieve the symptoms of hyponatremia, decrease intracranial pressure to lower the risk of complications and avoid overcorrection of hyponatremia.

How to prevent low sodium?

Here are some tips to help you lower your risk of developing low sodium (hyponatremia):

Follow your doctor’s treatment plan for conditions that can cause low sodium, for example, a medical history of adrenal gland insufficiency.
Learn the signs and symptoms of hyponatremia and when to seek medical attention if you have risk factors for hyponatremia (for example, diuretic therapy).
Avoid over-hydrating during high-intensity activities such as marathons.
Drink sports beverages that contain electrolytes instead of plain water during physically demanding activities.
Avoid drinking too much water (a lack of thirst and a pale yellow color in your urine are good indicators that you are getting enough water).