Syndrome of Inappropriate Antidiuretic Hormone (SIADH)

Syndrome of inappropriate antidiuretic hormone is a condition in which extra antidiuretic hormone (ADH) is produced in the body. ADH controls water levels in the body. When too much of the hormone is produced, it can cause problems such as low salt (sodium) levels in your blood and reduced urine production.

When this happens, the body retains too much water, which can cause various symptoms. Symptoms can range from mild to severe. SIADH is most common in people who are hospitalized for another reason.

What are the causes?

This condition may be caused by:

• Tumors.
• Injury to the brain.
• Infection or inflammation in the brain, such as meningitis or encephalitis.
• Lung infections or diseases.
• Cancer.
• Major surgery.
• Extreme exercise.
• Stroke.
• Guillain–Barré syndrome (GBS).
• Medicines, including chemotherapy drugs, NSAIDs, and pain medicines.
• Problems with breathing (respiratory failure).
• AIDS.

What increases the risk?

The following factors may make you more likely to develop this condition:

• Increasing age.
• Recent major surgery.
• Hospitalization.

What are the signs or symptoms?

Symptoms of this condition include:

• Irritability.
• Muscle cramps.
• Nausea or vomiting.
• Mental changes, such as memory problems, aggressiveness, confusion, or hallucinations.
• Seizure.
• Coma.

How is this diagnosed?

This condition may be diagnosed based on:

• Your medical history.
• A physical exam.
• Blood tests.
• Urine tests.
• Chest X-ray or brain scan.

How is this treated?

Treatment for this condition focuses on relieving symptoms. Treatment may include:

• Restricting fluid intake.
• Receiving sterile salt water (saline) slowly through an IV.
• Medicines to help remove water from the body (diuretics).
• Medicines to help control sodium levels.

Initial treatment for SIADH is done in a hospital, so your health care team can monitor your condition closely.

Other treatments may focus on treating the underlying cause of the condition.

Follow these instructions at home:

• Follow your health care provider’s instructions on restricting your intake of fluids.
• Take over-the-counter and prescription medicines only as told by your health care provider.
• Keep all follow-up visits as told by your health care provider. This is important.

Contact a health care provider if you:

• Have muscle cramps.
• Are nauseous or you vomit.

Get help right away if you have:

• A seizure.
• Loss of consciousness.
• Mental changes, such as memory problems, aggressiveness, confusion, or hallucinations.

Summary

• Syndrome of inappropriate antidiuretic hormone (SIADH) is a condition in which extra antidiuretic hormone (ADH) is produced in the body.
• SIADH is most common in people who are hospitalized for another reason.
• Initial treatment for SIADH is done in the hospital setting in order to monitor your condition closely.
• Follow your health care provider’s instructions on restricting your intake of fluids.