Syndrome of Inappropriate Antidiuretic Hormone Secretion (SIADH)

What is syndrome of inappropriate antidiuretic hormone secretion (SIADH)?

SIADH occurs when excessive levels of antidiuretic hormones (hormones that help the kidneys, and body, conserve the correct amount of water) are produced. The syndrome causes the body to retain water and certain levels of electrolytes in the blood to fall (such as sodium). SIADH is rare in children.

What causes SIADH?

SIADH tends to occur in people with heart failure or people with a diseased hypothalamus (the part of the brain that works directly with the pituitary gland to produce hormones). In other cases, a certain cancer (elsewhere in the body) may produce the antidiuretic hormone, especially certain lung cancers. Other causes may include the following:

• meningitis - inflammation of the meninges, the membranes that cover the brain and spinal cord.
  
  
• encephalitis - inflammation of the brain.
  
  
• brain tumors
  
  
• psychosis
  
  
• lung diseases
  
  
• head trauma
  
  
• Guillain-Barré syndrome (GBS) - a reversible condition that affects the nerves in the body. GBS can result in muscle weakness, pain, and even temporary paralysis of the facial, chest, and leg muscles. Paralysis of the chest muscles can lead to breathing problems.
  
  
• certain medications
  
  
• damage to the hypothalamus or pituitary gland during surgery

What are the symptoms of SIADH?

Each child may experience symptoms differently. Symptoms, in more severe cases of SIADH, may include:

• nausea
• vomiting
• irritability
• personality changes, such as combativeness, confusion, and hallucinations
• seizures
• stupor
• coma

The symptoms of SIADH may resemble other problems or medical conditions. Always consult your child's physician for a diagnosis.

How is SIADH diagnosed?

In addition to a complete medical history and physical examination, to confirm diagnosis of SIADH, blood tests will need to be performed to measure sodium, potassium chloride levels, and osmolality (concentration of solution in the blood).

Treatment for SIADH:

Specific treatment for SIADH will be determined by your child's physician based on:

• your child's age, overall health, and medical history
• extent of the disease
• your child's tolerance for specific medications, procedures, or therapies
• expectations for the course of the disease
• your opinion or preference

The most commonly prescribed treatment for SIADH is fluid restriction of between 30 to 75 percent of normal fluid intake, depending on the severity of the disorder. If the condition is chronic, fluid restriction may need to be permanent. Treatment may also include:

• certain medications that inhibit the action of ADH (rarely used in children because of the side effects)
  
  
• surgical removal of a tumor that is producing ADH