Which Signs and Symptoms Are Consistent With SIADH?

Medically Reviewed on 9/22/2021
Syndrome of Inappropriate Antidiuretic Hormone (SIADH)
The most common cause of SIADH symptoms is hyponatremia (low sodium level), which can result in confusion, loss of appetite, disorientation, and more signs.

A low sodium level (hyponatremia) is the most common cause of symptoms associated with the syndrome of inappropriate secretion of antidiuretic hormone (SIADH). If hyponatremia develops gradually, it does not cause any noticeable symptoms. However, signs and symptoms may be prominent in severe or rapid onset of hyponatremia and can include:

Table. Signs and symptoms of SIADH
System Signs and symptoms
General
  • Weakness
  • Fatigue
  • Malaise
Neurologic
  • Altered mental status
  • Headache
  • Lethargy, irritability
  • Delirium
  • Psychosis
  • Personality changes
  • Tremors
  • Impaired balance or coordination
  • Seizures
  • Coma
  • Confusion
  • Disorientation
Cardiovascular
  • Normal blood pressure
  • Usually, a normal pulse
  • Normal skin elasticity
Gastrointestinal
  • Loss of appetite
  • Nausea, vomiting
  • Diarrhea
  • Thirst
  • Abdominal cramps
Renal
  • Weight gain
  • Less urine (less than 400 cc in 24 hours)
  • Lack of voluntary control over urination
Musculoskeletal
  • Muscle cramps
  • Hyporeflexia
  • Twitching or jerking of a muscle or group of muscles

What is SIADH?

Syndrome of inappropriate secretion of antidiuretic hormone (SIADH) occurs when the body produces an excess antidiuretic hormone (ADH). ADH helps the kidney retain the appropriate amount of water. When the body produces excess ADH, it leads to more water retention and sodium level depletion (due to dilution) in the blood.

What is the most common cause of SIADH?

Syndrome of inappropriate secretion of antidiuretic hormone may be caused by the following:

When should I contact my healthcare provider?

Contact the doctor if you experience the following symptoms:

Seek immediate care or call 911 if someone has the following severe symptoms:

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Medically Reviewed on 9/22/2021
References
Thomas CP. Syndrome of Inappropriate Antidiuretic Hormone Secretion (SIADH) Medication. Medscape. https://emedicine.medscape.com/article/246650-medication

Medline Plus. Syndrome of Inappropriate Antidiuretic Hormone Secretion. https://medlineplus.gov/ency/article/000314.htm

Mayo Clinic. Hyponatremia. https://www.mayoclinic.org/diseases-conditions/hyponatremia/symptoms-causes/syc-20373711