Hypernatremia in Children - Causes, Symptoms, and Management

Introduction:

Hypernatremia is a common presentation seen in children and elderly people. It is due to severe water loss and extra solutes in the body. This condition can be dangerous if it is left untreated. Most cases are reported in children due to decreased water and fluid intake, as they cannot interpret their need for fluids or water on their own. This may result in diarrheal episodes. Hypernatremia is also seen in severe illnesses and those with neurologic impairments. Although hypernatremia is a common clinical presentation, it can also be fatal if not treated at the right time.

How Is Hypernatremia Classified?

Hypernatremia (a higher sodium level is called hypernatremia) is classified into three main types depending on their severity and clinical presentation: mild, moderate, and severe. Moderate to severe cases may cause shrinkage of the brain tissues, rupture of the blood vessels, and hemorrhage, causing permanent injury to the tissues.

• Mild Hypernatremia: When the serum sodium level is 146 to 149 mmol/L.

• Moderate Hypernatremia: The serum sodium concentration is 150 to 169 mmol/L.

• Severe Hypernatremia: Serum sodium concentration is more than 170 mmol/L.

Mechanisms or Pathophysiology of Hypernatremia

In hypernatremia, the cells become dehydrated, and the body has a water deficit. It may be due to complete water loss or the gain of more sodium ions. However, 90 percent of hypernatremia is due to complete water loss. Only a few cases are due to excess sodium load during intravenous transfusions or salt poisoning. Three mechanisms cause hypernatremia.

1. Pure water depletion.

2. The rate of water depletion is more than that of sodium depletion.

3. Presence of excess sodium ions.

Who Is at High Risk?

Hypernatremia can occur in any individual, irrespective of age and gender. However, infants and intubated patients with chronic illnesses are highly vulnerable to hypernatremia. Infants who receive inadequate breast milk and other gastrointestinal problems are susceptible to hypernatremia and dehydration. In patients with neurological impairments and long-term intubation, the thirst mechanism is compromised, resulting in hypernatremia.

What Causes Hypernatremia?

The cause of hypernatremia can be divided into two categories.

1. Hypernatremia Due to Water Deficits:

• Gastrointestinal disturbances that cause chronic diarrhea.

• Excess sweating and water loss from the skin.

• Acute tubular necrosis.

• Increased urination (polyuria).

• Less fluid intake or inadequate breast milk supply in infants.

2. Hypernatremia Due to Sodium Excess:

• Accidental ingestion of large amounts of salt (salt poisoning).

• Endocrine disturbances:

• Hyperaldosteronism is a condition in which the adrenal gland releases too much of the hormone aldosterone into the bloodstream, causing low potassium and increased sodium concentration.

• Presence of nephrotic syndrome, congestive cardiac failure, or patients on steroid therapy.

What Is the Clinical Presentation of Hypernatremia?

• Signs of dehydration.

• Altered mental state with irritability, agitation, and lethargy.

• Vomiting, muscle twitching, and tremors.

• A high-pitched cry is seen in infants.

• Increased pulse rate and rapid breathing (tachycardia).

• Increased frequency of urination (polyuria) and increased thirst (polydipsia).

• In some individuals, there is an impaired thirst mechanism.

In severe cases, the following symptoms are noticed:

• Lethargy.

• Hyperreflexia and increased muscle tone.

• Seizure episodes.

• Coma.

What Is Hypernatremia in Children?

Hypernatremia in children occurs during the newborn period. It can be observed among those with insufficient breastfeeding intake. In older children, hyponatremia is due to excess water loss, either from gastroenteritis or systemic infection.

What Is the Differential Diagnosis of Hypernatremia?

• Diabetes Mellitus: The condition where the body cannot control the amount of blood glucose.

• Hypertonic Dehydration: Dehydration is due to the body's imbalance of water and salt.

• Nephrogenic Diabetes Insipidus: This is a condition in which the kidneys cannot regulate the amount of water excreted in the body.

• Salt Poisoning: Accidental ingestion of large amounts of salt or sodium.

• Cirrhosis: A severe liver disease where scar tissues replace the healthy liver cells.

• Hypocalcemia: Less serum calcium in the blood.

• Thirst Defect: Absence of thirst sensations.

How to Diagnose Hypernatremia?

Diagnoses are based on physical examination and the history obtained from the parents of the affected children. The following tests are done to confirm the diagnosis of hypernatremia.

1. Serum Tests: This is a laboratory procedure where the serum sodium concentration is measured.

2. Special Imaging Tests:

• Computed Tomography (CT Scan): This helps detect tumors, intracranial abnormalities, or infectious diseases such as tuberculosis and sarcoidosis.

• Magnetic Resonance Imaging (MRI): This produces more detailed information than computed tomography. In some cases, CT scans may not provide adequate information, in which case an MRI is suggested.

How to Manage Hypernatremia?

The treatment of hypernatremia includes identifying the exact cause and correcting the body's sodium and water imbalance.

• Replacement of the intravascular volume. Administration of fluids is initiated either orally or through feeding tubes.

• In conscious patients, oral hydration therapy is effective.

• In unconscious patients, intravenous administration of the fluids is given.

• In cases of severe dehydration, the first treatment line should focus on resuscitation to stabilize the patient. It is then followed by isotonic fluid administration before correcting the water loss.

• In cases of chronic hypernatremia (more than 48 hours), treatment should be done slowly. Lowering the sodium concentration rapidly may cause the perfusion of sodium ions into the brain cells, causing cerebral edema. Hence, serum sodium should be monitored carefully, and at most, 12 meq should be lowered in 24 hours.

• In some cases, seizure episodes are encountered during the treatment of hypernatremia. This may suggest cerebral edema, venous sinus thrombosis, or cerebral infarction. In such cases, the fluid administration should be suspended temporarily, and CT imaging should be done to assess the problem.

What Is Free Water Deficit in Hypernatremia?

The free water deficit in hypernatremia is calculated by estimating total body water. This helps determine the volume of water required to correct dehydration or reach the desired sodium level in the blood serum. It is done during the initial stages of fluid replacement therapy.

What Are the Complications of Hypernatremia?

• The most severe complication of hypernatremia is the rupture of blood vessels in the brain, known as the subarachnoid or subdural hemorrhage, which can cause permanent brain damage or death.

• If the hypernatremia is detected early and the treatment is done, then serious complications like brain damage, seizures, or death can be prevented.

Conclusion:

Hypernatremia can be a life-threatening condition if it is not treated. Identifying the exact cause and treating it significantly reduces the mortality rates. Regular monitoring of the fluids and electrolytes is essential. In cases of severe hypernatremia, treatment may take several days. Special care should be taken in cases of cerebral edema and seizures.