Inappropriate Antidiuretic Hormone Secretion (SIADH)

What is Inappropriate Antidiuretic Hormone Secretion (SIADH)?

Antidiuretic hormone (ADH) is produced by the hypothalamus (area of the brain) and released by the pituitary gland (located at the base of the brain). ADH helps in controlling the amount of water excreted by the kidneys through urine. Inappropriate antidiuretic hormone secretion (SIADH) is a syndrome wherein the body secretes high levels of antidiuretic hormone (ADH). This disorder leads to excess water retention in the body.

What are its main signs and symptoms?

The common signs and symptoms of SIADH include:

• Headache
• Nausea
• Vomiting
• Mental alterations which include
  • Confusion
  • Problems with memory (Read more: Memory loss treatment)

• Balance related issues leading to falls
• In severe cases, it can cause seizures or even coma

What are its main causes?

Factors causing rise in ADH levels in the body can lead to SIADH, these factors include:

• Medications, which include drugs for:
  • Hormonal medications (vasopressin or ADH).
  • Type 2 diabetes
  • Seizure
  • Antidepressants
  • Blood pressure or heart disease related
  • Cancer
  • Anaesthesia or surgery under general anaesthesia

• Disorders of the brain, which include :
  • Stroke
  • Injury
  • Infections

• Lung disease, which includes:
  • Chronic infections
  • Tuberculosis
  • Pneumonia
  • Cancer

• Mental disorders
• Disorder of the hypothalamus or pituitary
• Cancers of the following organs/body systems:
  • Leukaemia (Blood cancer)
  • Pancreas
  • Small intestine 
  • Brain

How is it diagnosed and treated?

The physician will conduct a complete physical examination of the patient to find the cause of symptoms, followed by some tests which include:

• Tests for blood and urine sodium level measurement
• Tests for evaluating blood and urine osmolality
• Comprehensive metabolic panel (test to assess kidney and liver function, acid/base balance, electrolytes, and blood sugar)

Depending on the cause of SIAD the treatment includes:

• Restricting the intake of fluid. The amount of fluid you can consume will be decided by the physician.
• Oral or intravenous medications may be prescribed for blocking the effects of ADH on the kidneys This promotes the excretion of excess water by the kidney
• Treating the root cause of the disorder as follows:

1. Surgery when a tumour is the cause.
2. Change the dosage of medications or alter the medications causing abnormal production of ADH.