Syndrome of Inappropriate Antidiuretic Hormone Secretion (SIADH)
To view the entire topic, please log in or purchase a subscription.
Medicine Central™ is a quick-consult mobile and web resource that includes diagnosis, treatment, medications, and follow-up information on over 700 diseases and disorders, providing fast answers—anytime, anywhere. Explore these free sample topics:
-- The first section of this topic is shown below --
Basics
Syndrome of inappropriate secretion of antidiuretic hormone (SIADH) is a common cause of hyponatremia in hospitalized patients.
Description
- The syndrome of inappropriate secretion of antidiuretic hormone (SIADH) is a disorder with impaired water excretion (concentrated urine), caused by abnormal production of antidiuretic hormone (ADH) despite low serum osmolality.
- Decreased urinary electrolyte-free water excretion leads to dilutional hyponatremia (total body sodium [Na] levels may be normal or near-normal, but the patient’s total body water is increased).
- Often secondary to medications but may be associated with an underlying disorder, such as neoplasm, a pulmonary disorder, or CNS disease
- Synonym(s): syndrome of inappropriate secretion of ADH; syndrome of inappropriate antidiuresis
Epidemiology
Incidence
- Often found in the hospital setting, where incidence can be as high as 35%
- Predominant age: elderly
- Predominate sex: females > males
Prevalence
It is also prevalent in hospitalized perioperative patients in response to stress, hypotonic fluids, and drugs.
Etiology and Pathophysiology
- Drugs:
- Antidepressants (e.g., SSRIs, tricyclics, monoamine oxidase inhibitors [MAOIs])
- Antineoplastic drugs (e.g., vincristine, vinblastine, cisplatin, cyclophosphamide)
- Antipsychotic agents (e.g., risperidone, quetiapine, phenothiazines, haloperidol)
- Analgesics (e.g., duloxetine, pregabalin, tramadol, NSAIDs)
- Anticonvulsants (e.g., carbamazepine, oxcarbazepine, valproic acid, phenytoin)
- Others (e.g., vasopressin, DDAVP, oxytocin, ciprofloxacin, α-interferon, ecstasy)
- Malignancies (ectopic ADH production):
- Bronchogenic carcinoma
- Lymphoma
- Mesothelioma
- Small cell carcinoma of the lung
- Pancreatic carcinoma
- Thymoma
- Pulmonary conditions:
- Asthma/COPD/pneumothorax
- Atelectasis
- Cystic fibrosis
- Positive pressure mechanical ventilation
- Pneumonia (viral, bacterial)
- Pulmonary tuberculosis (TB)
- Sarcoidosis
- Neurologic causes:
- Brain tumor
- CNS injury (i.e., subarachnoid hemorrhage, trauma, stroke)
- CNS lupus
- Encephalitis
- Epilepsy
- Guillain-Barré syndrome
- Intracranial surgery
- Meningitis
- Multiple sclerosis
- Nephrogenic/hereditary:
- A gain of function mutation in the gene for vasopressin 2 receptors (V2R)
- Other:
- Acute intermittent porphyria
- Delirium tremens
- HIV infection/AIDS
- Rocky Mountain spotted fever
Genetics
- 10% of patients have an X-linked mutation of V2R.
- Polymorphisms in TRPV4 gene
Risk Factors
- Advanced age
- Postoperative status
- Institutionalization
- Use of predisposing drugs
General Prevention
- Search for the cause, if unknown.
- Reduce/change medications, if drug-induced.
- Lifelong restriction of fluid intake
Commonly Associated Conditions
See “Etiology and Pathophysiology.”
-- To view the remaining sections of this topic, please log in or purchase a subscription --
Basics
Syndrome of inappropriate secretion of antidiuretic hormone (SIADH) is a common cause of hyponatremia in hospitalized patients.
Description
- The syndrome of inappropriate secretion of antidiuretic hormone (SIADH) is a disorder with impaired water excretion (concentrated urine), caused by abnormal production of antidiuretic hormone (ADH) despite low serum osmolality.
- Decreased urinary electrolyte-free water excretion leads to dilutional hyponatremia (total body sodium [Na] levels may be normal or near-normal, but the patient’s total body water is increased).
- Often secondary to medications but may be associated with an underlying disorder, such as neoplasm, a pulmonary disorder, or CNS disease
- Synonym(s): syndrome of inappropriate secretion of ADH; syndrome of inappropriate antidiuresis
Epidemiology
Incidence
- Often found in the hospital setting, where incidence can be as high as 35%
- Predominant age: elderly
- Predominate sex: females > males
Prevalence
It is also prevalent in hospitalized perioperative patients in response to stress, hypotonic fluids, and drugs.
Etiology and Pathophysiology
- Drugs:
- Antidepressants (e.g., SSRIs, tricyclics, monoamine oxidase inhibitors [MAOIs])
- Antineoplastic drugs (e.g., vincristine, vinblastine, cisplatin, cyclophosphamide)
- Antipsychotic agents (e.g., risperidone, quetiapine, phenothiazines, haloperidol)
- Analgesics (e.g., duloxetine, pregabalin, tramadol, NSAIDs)
- Anticonvulsants (e.g., carbamazepine, oxcarbazepine, valproic acid, phenytoin)
- Others (e.g., vasopressin, DDAVP, oxytocin, ciprofloxacin, α-interferon, ecstasy)
- Malignancies (ectopic ADH production):
- Bronchogenic carcinoma
- Lymphoma
- Mesothelioma
- Small cell carcinoma of the lung
- Pancreatic carcinoma
- Thymoma
- Pulmonary conditions:
- Asthma/COPD/pneumothorax
- Atelectasis
- Cystic fibrosis
- Positive pressure mechanical ventilation
- Pneumonia (viral, bacterial)
- Pulmonary tuberculosis (TB)
- Sarcoidosis
- Neurologic causes:
- Brain tumor
- CNS injury (i.e., subarachnoid hemorrhage, trauma, stroke)
- CNS lupus
- Encephalitis
- Epilepsy
- Guillain-Barré syndrome
- Intracranial surgery
- Meningitis
- Multiple sclerosis
- Nephrogenic/hereditary:
- A gain of function mutation in the gene for vasopressin 2 receptors (V2R)
- Other:
- Acute intermittent porphyria
- Delirium tremens
- HIV infection/AIDS
- Rocky Mountain spotted fever
Genetics
- 10% of patients have an X-linked mutation of V2R.
- Polymorphisms in TRPV4 gene
Risk Factors
- Advanced age
- Postoperative status
- Institutionalization
- Use of predisposing drugs
General Prevention
- Search for the cause, if unknown.
- Reduce/change medications, if drug-induced.
- Lifelong restriction of fluid intake
Commonly Associated Conditions
See “Etiology and Pathophysiology.”
There's more to see -- the rest of this topic is available only to subscribers.