Dilutional Hyponatremia - Causes, Symptoms, Diagnosis, and Treatment

Introduction

When people drink too much water without getting enough electrolytes, they develop dilutional hyponatremia. It is commonly known as water intoxication, which can be fatal. It develops when the water intake exceeds the kidney's ability to eliminate water.

The body requires enough salts and other ions, referred to as electrolytes, to maintain healthy cell activity. If a person consumes excess water without proper electrolytes, water can migrate into the body's cells and enlarge them.

What Is Dilutional Hyponatremia?

Hyponatremia occurs when the level of sodium in the blood is abnormally low. As an electrolyte, sodium aids in controlling the volume of water in and around the cells. When a person has hyponatremia, the body's sodium levels are diluted for reasons such as an underlying medical condition or drinking too much water. The main problem is excess water that dilutes the sodium levels. As a result, the water moves into cells, leading to their swelling. The swelling can cause brain cell damage. It can further progress to seizures or coma.

The goal of treating hyponatremia is to treat the underlying problem. Depending on what caused the hyponatremia, one may only need to drink less water. On the other hand, intravenous (into the vein) electrolyte solutions and medications are required in other hyponatremia cases. Hyponatremia is the most frequent chemical abnormality seen among patients admitted to a hospital and in outpatient clinics.

What Are the Causes of Dilutional Hyponatremia?

Dilutional hyponatremia can be caused by several factors that result in excess water relative to sodium in the body. Some common causes of dilutional hyponatremia include:

• Excessive Water Intake: Drinking excessive amounts of water without replenishing sodium levels can dilute the sodium in the bloodstream.

• Child Abuse: One of the causes of dilutional hyponatremia is forced water intake as child abuse. Symptoms of dilutional hyponatremia occur more quickly in children. It is attributed to the smaller space in which the brain can expand because of their larger brain-to-skull size ratio. The condition is called hyponatremic encephalopathy.

• Latrogenic Causes: Iatrogenic (doctor-induced) infusion of excessive hypotonic fluid (a fluid that contains less osmotic pressure than body fluids) is another common cause.

• Psychiatric Disorders: Psychiatric patients lose sodium through increased fluid output. The reasons include self-induced vomiting and laxative abuse leading to diarrhea.

• Medications: A few medications like diuretics, antidepressant pills, and antipsychotics, can affect the body's fluid and electrolyte balance, leading to dilutional hyponatremia.

• Syndrome of Inappropriate Antidiuretic Hormone (SIADH): It is a rare condition that causes excessive release of antidiuretic hormone (ADH), which can lead to water retention and dilutional hyponatremia.

• Endurance Sports: During prolonged endurance sports, such as marathons, athletes may consume excessive amounts of water without replenishing sodium levels, leading to dilutional hyponatremia.

What Are the Symptoms of Dilutional Hyponatremia?

The symptoms of dilutional hyponatremia can vary depending on the condition's severity. In mild cases, symptoms may be absent or minimal. On the other hand, in severe cases, dilutional hyponatremia can be life-threatening. Some common symptoms of severe dilutional hyponatremia include:

• Nausea and vomiting.

• Headache.

• Confusion or disorientation.

• Seizures.

• Muscle weakness, cramps, or spasms.

• Fatigue or lethargy.

• Coma or loss of consciousness.

In severe dilutional hyponatremia, symptoms can progress rapidly, leading to brain swelling, respiratory arrest, and death. Hence, a proper diagnosis and treatment plan is essential to avoid unwanted complications and ensure a favorable outcome.

It is important to note that the symptoms of dilutional hyponatremia can be similar to dehydration and heat stroke. Therefore, it is important to seek medical attention if any of these symptoms occur during or after physical activity or in situations where fluid intake has been high.

How Is Dilutional Hyponatremia Diagnosed?

The diagnosis of dilutional hyponatremia is based on detailed history, physical examination, and laboratory and image findings. Some common diagnostic tests for dilutional hyponatremia include:

• Blood Tests: They are used to measure the sodium levels in the blood. In dilutional hyponatremia, the sodium levels are usually lower than normal.

• Urine Tests: Urine tests can determine whether the kidneys are functioning properly and the body is excreting excess water.

• Imaging Studies: Imaging studies, such as CT (computed tomography) scans or MRIs (magnetic resource imaging), may be used to evaluate the brain and rule out other possible causes of the symptoms. Chest X-ray images can also be helpful. A patients' fluid status and lung pathology can be diagnosed using a chest X-ray.

• Medical History: When the medical history is taken by the physician it is essential to identify any underlying medical conditions. It can further rule out medications responsible for the development of dilutional hyponatremia.

• Physical Examination: A proper physical examination can pave way to identify any neurological or other symptoms associated with dilutional hyponatremia.

What Treatment Should Be Done For Dilutional Hyponatremia?

The treatment of dilutional hyponatremia depends on how severe the condition is and the presence of any underlying cause. Some common treatment options for dilutional hyponatremia include:

• Fluid Restriction: In mild cases of dilutional hyponatremia, a fluid restriction may be sufficient to allow the body to eliminate excess water and restore normal sodium levels.

• Sodium Replacement: In more severe cases of dilutional hyponatremia, sodium replacement may be necessary to restore normal sodium levels. This can be achieved through oral sodium supplementation or intravenous (IV) administration of saline or other sodium-containing solutions.

• Diuretics: In some cases, diuretics may be used to help the kidneys eliminate excess water and restore normal sodium levels.

• Treatment of Underlying Medical Conditions: If dilutional hyponatremia is caused by an underlying medical condition, such as heart failure or SIADH, treatment of the underlying condition is essential to prevent future occurrences of dilutional hyponatremia.

• Regular Patient Monitoring: The fluid and electrolyte levels of patients with dilutional hyponatremia may be in need of keen monitoring to prevent the recurrence of the condition.

A doctor may prescribe Tolvaptan or Conivaptan to correct blood sodium levels in severe hyponatremia. Both medications are used to treat hyponatremia in patients with heart failure or SIADH. The doctor will also treat underlying medical problems, including heart and kidney failure and liver cirrhosis (these conditions cause hyponatremia).

Conclusion

Dilutional hyponatremia can cause an altered mental status, seizures, coma, and death. Hence, it is a potentially serious condition caused by various factors. Early recognition and treatment are important to prevent complications and ensure a favorable outcome. Prevention involves maintaining proper fluid and electrolyte balance during endurance sports and other activities that involve significant fluid loss. With proper treatment, many people recover completely from dilutional hyponatremia.