Diagnosing Fluid & Electrolyte Disorders in Children

NYU Langone doctors are experienced in identifying and treating infants and children who develop fluid and electrolyte disorders, a group of conditions that temporarily affect fluid and mineral levels in the body. Electrolytes are electrically charged minerals—such as sodium, potassium, calcium, phosphorous, and magnesium—that are critical for nerve and muscle cell function.

Causes and Risk Factors

Electrolytes are found in fluids in the body. Dehydration can upset the delicate balance of electrolytes in an infant or child. Children are especially vulnerable to dehydration due to their small size and fast metabolism, which causes them to replace water and electrolytes at a faster rate than adults.

An illness that causes severe vomiting, diarrhea, and a high fever increases the risk of a fluid and electrolyte disturbance, as does taking medication that causes excessive urination. Profuse sweating from physical exertion can also increase the risk of dehydration.

Fluid and electrolyte disturbances are common in children with a serious underlying medical condition. For instance, children with chronic kidney disease, a condition that affects the ability of these organs to maintain proper fluid and electrolyte levels, are at risk.

Conditions that affect the production of thyroid hormones and parathyroid hormones, which help regulate calcium and other electrolytes, can also make a child susceptible to a fluid and electrolyte imbalance. Children with heart disease may retain sodium and water, and develop abnormal electrolyte levels.

Those who have cancer and receive a bone marrow transplant—which increases the risk of infections and fever—or take chemotherapy medications that cause kidney problems are also at higher risk of developing a fluid and electrolyte imbalance.


Signs of a fluid or electrolyte disorder vary widely. Mild electrolyte disorders often cause no symptoms. Symptoms of a more severe imbalance depend on the type of disorder.

Dehydration may make your child’s urine appear darker than usual. Other electrolyte disorders cause confusion, weakness, cramping, and muscle spasms. Some can cause difficulty breathing, dizziness, and a rapid heart rate. Parents who notice any of these symptoms, especially if a child has an underlying medical condition or a fever, should have their child evaluated by a doctor immediately.

Rapid diagnosis and treatment are important. Severe dehydration and the accompanying electrolyte disturbances can reduce blood and mineral flow to vital organs, including the brain, heart, and liver. In rare instances, this can make brain tissue swell or shrink, causing seizures, or life-threatening disturbances in heart rhythm, known as arrhythmia.

Doctors at NYU Langone use the results of a physical exam and laboratory tests to diagnose fluid and electrolyte disorders in children.

Physical Exam

During a physical exam, your child’s doctor assesses the severity of a fluid and electrolyte disturbance and looks for clues to identify the cause. The doctor asks if your child has been ill recently and whether he or she has had any unusual symptoms, such as muscle cramps, dizziness, rapid heart rate, or confusion.

The doctor measures your child’s blood pressure to see if it is low, which may suggest that the child is dehydrated. In addition, he or she may examine your child’s skin to check its elasticity. The doctor may also test your child’s reflexes, which can be affected by dehydration.

Laboratory Tests

Blood and urine tests are used to confirm an electrolyte imbalance and determine its severity. Depending on how ill your child is, these tests can be performed using blood and urine samples taken in the doctor’s office or the hospital. Laboratory results are usually available quickly.

Based on the results of these tests and any underlying medical conditions your child may have, our doctors develop an appropriate treatment plan to correct a fluid and electrolyte imbalance and prevent complications.

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