SIADH is when the body makes too much antidiuretic hormone (ADH). ADH is a hormone that normally helps the kidneys keep the correct amount of water in the body. SIADH causes the body to retain more water than needed. This often leads to low sodium levels in the blood (called hyponatremia). SIADH is a rare condition in children. It most often happens to children who are in the hospital.

SIADH often occurs in people with heart failure or with a brain injury that affects the hypothalamus. The hypothalamus is the part of the brain that works with the pituitary gland to make hormones. Other causes may include:

• Inflammation of the membranes that cover the brain and spinal cord (meningitis).
• Inflammation of the brain (encephalitis).
• Brain tumor and other tumors.
• Psychosis.
• Lung disease, especially pneumonia.
• Head injury.
• Guillain-Barré syndrome.
• Certain medicines, such as chemotherapy and anti-seizure medicines.
• Damage to the hypothalamus or pituitary gland during surgery.
• Low amounts of thyroid or parathyroid hormones.
• HIV.
• Hereditary causes.

Symptoms can occur a bit differently in each child. In severe cases, symptoms can include:

• Nausea or vomiting.
• Cramps or tremors.
• Depressed mood.
• Irritability.
• Memory problems.
• Personality changes, such as anger and confusion.
• Hallucinations.
• Seizures.
• Coma.

Many of these symptoms may be caused by other health problems. Make sure your child sees their doctor for a diagnosis.

The doctor will ask about your child's symptoms and health history. They may also ask about your family's health history. The doctor will do a physical exam of your child. Your child may also have blood and urine tests. These tests are done to check:

• Sodium levels in the body (serum and urine).
• Osmolality (concentration of ions like sodium) dissolved in the urine and blood.

The most common treatment for SIADH is limiting how much fluid and water your child has. If the condition is ongoing (chronic), your child may need to limit fluids for life. Treatment may also include:

• A medicine called a vasopressin or desmopressin that blocks the action of ADH.
• Surgery to remove a tumor that is making ADH.
• Other medicines to help manage body fluid volume.

Complications of SIADH depend on how low blood sodium levels are. Possible mild complications include:

• Headaches.
• Depression.
• Memory problems.
• Muscle cramps.
• Tremors.

Possible severe complications include:

• Hallucinations.
• Seizures.
• Respiratory failure.
• Coma.
• Death.

A child with chronic SIADH may need to permanently limit how much fluid they have. Work with your child's doctors to create an ongoing plan to manage your child's condition.

Get medical attention right away if your child has symptoms of SIADH (not making urine).

Call the doctor if your child has chronic SIADH and:

• You have trouble restricting your child's fluid intake.
• Your child has new symptoms.

• SIADH is when the body makes too much antidiuretic hormone (ADH). This is a hormone that normally helps the kidneys conserve the correct amount of water in the body.
• SIADH causes the body to retain water. This lowers the level of sodium in the blood. SIADH is rare in children.
• SIADH tends to occur in people with heart failure or with a brain injury that affects the hypothalamus.
• In severe cases, symptoms can include nausea or vomiting, cramps or tremors, irritability, and memory problems.
• The most common treatment for SIADH is limiting how much fluid and water your child has. A child with chronic SIADH may need to permanently limit fluids.
• Treatment may also include medicines or surgery.

Tips to help you get the most from a visit to your child's doctor:

• Know the reason for the visit and what you want to happen.
• Before your visit, write down questions you want answered.
• At the visit, write down the name of a new diagnosis and any new medicines, treatments, or tests. Also write down any new instructions your doctor gives you for your child.
• Know why a new medicine or treatment is prescribed and how it will help your child. Also know what the side effects are.
• Ask if your child's condition can be treated in other ways.
• Know why a test or procedure is recommended and what the results could mean.
• Know what to expect if your child does not take the medicine or have the test or procedure.
• If your child has a follow-up appointment, write down the date, time, and purpose for that visit.
• Know how you can contact your child's doctor after office hours. This is important if your child becomes ill and you have questions or need advice.