Which electrolyte disorder is most likely to trigger early symptoms of SIADH?

Syndrome of inappropriate antidiuretic hormone secretion 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 (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

• Thyroid or parathyroid hormone deficiencies

• HIV

• Hereditary causes

What are the symptoms of SIADH?

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

• Nausea or vomiting

• Cramps or tremors

• Depressed mood,memory impairment

• Irritability

• Personality changes, such as combativeness, confusion, and hallucinations

• Seizures

• Stupor or coma

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

How is SIADH diagnosed?

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

Treatment for SIADH

Specific treatment for SIADH will be determined by your doctor based on:

• Your age, overall health, and medical history

• Extent of the disease

• Your 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 and water restriction. If the condition is chronic, fluid restriction may need to be permanent. Treatment may also include:

Antidiuretic hormone (ADH) is produced by an area of the brain called the hypothalamus. This hormone is stored in and released by the pituitary gland. ADH controls how your body releases and conserves water.

When ADH (also called vasopressin) is produced in excess, the condition is called syndrome of inappropriate antidiuretic hormone (SIADH). This overproduction can occur in places other than the hypothalamus.

SIADH makes it harder for your body to release water. Additionally, SIDAH causes levels of electrolytes, like sodium, to fall as a result of water retention. A low sodium level or hyponatremia is a major complication of SIADH and is responsible for many of the symptoms of SIADH. Early symptoms may be mild and include cramping, nausea, and vomiting. In severe cases, SIADH can cause confusion, seizures, and coma.

Treatment usually begins with limiting fluid intake to prevent further buildup. Additional treatment will depend on the cause.

Another name for the syndrome is “ectopic ADH secretion.”

Causes of SIADH

A variety of conditions can trigger abnormal ADH production, including:

• brain infections
• bleeding in or around the brain
• head trauma
• hydrocephalus
• Guillian-Barre syndrome
• multiple sclerosis
• infections including HIV and Rocky Mountain spotted fever
• cancers of the lung or gastrointestinal or genitourinary tract, lymphoma, sarcoma
• lung infections
• asthma
• cystic fibrosis
• medications
• anesthesia
• hereditary factors
• sarcoidosis

Symptoms of SIADH

SIADH makes it difficult for your body to get rid of excess water. This causes a buildup of fluids as well as abnormally low sodium levels.

Symptoms may be mild and vague at first, but tend to build. Severe cases may involve these symptoms:

• irritability and restlessness
• loss of appetite
• cramps
• nausea and vomiting
• muscle weakness
• confusion
• hallucinations
• personality changes
• seizures
• stupor
• coma

Diagnosing SIADH

Your doctor will ask for your complete medical history and current symptoms. Your doctor should know whether you are taking any over-the-counter or prescription medications or supplements. Diagnosis usually begins with a physical exam. Often, a urine sample is also required.

Blood tests, specifically one called an ADH test, can measure circulating ADH levels in the blood, but it’s very difficult to obtain an accurate level. According to the University of Rochester Medical Center, normal values for ADH range from 0-5 picograms per milliliter. Higher levels could be the result of SIADH. Most cases of SIADH are accurately diagnosed using serum and urine sodium and osmolality values as well as clinical presentation.

Following diagnosis of SIADH, the next step will be to identify the condition that caused it to occur.

Treatment and prognosis for SIADH

The first line of treatment is to limit fluid intake to avoid further buildup. Medications may include those that can reduce fluid retention, such as furosemide (Lasix), and those that can inhibit ADH, like demeclocycline.

What electrolyte disorder is associated with SIADH?

What is the most common cause of SIADH?

Is potassium high or low in SIADH?

What labs are abnormal with SIADH?