Syndrome+of+Inappropriate+Antidiuretic+Hormone+(SIADH)

Syndrome of Inappropriate Antidiuretic Hormone (SIADH)/ Schwartz-Bartter syndrome-

Pathophysiology- As the name suggests this syndrome is caused by over secretion of Antidiuretic hormone (ADH) also known as vasopressin. When the body needs to retain more water ADH is secreted by the posterior pituitary gland. This will cause the kidneys to reabsorb water and put it back into systemic circulation. With SIADH ADH is release even when the body does not need to retain more water. This leads to fluid retention (increasing plasma volume) and hyponatremia. The increase in plasma volume increases glomerular filtration rate (GFR) and inhibit the release of renin and aldosterone. This increased sodium loss in urine further exacerbating the hyponatremia.

Signs/Symptoms-
 * Mild- Weakness, muscle cramps, loss of appetite, nausea and vomiting, and fatigue.
 * As fluid retention increase patient may present with
 * Increase weight gain,
 * Nervous system changes,
 * Personality changes,
 * Confusion,
 * Extreme muscle weakness.
 * Fluid overload-
 * Increased pulse quality,
 * Increased neck vein distention,
 * Crackles in lungs,
 * Increased peripheral edema (dependent edema is usually not present because only water is retained, not salt)
 * Reduced urine output.
 * May lead to pulmonary edema and heart failure (increased risk with patients with coexisting cardiac, kidney, pulmonary, or liver problems).
 * As hyponatremia increase as levels drop resulting in
 * Lethargy and headache
 * Decreased responsiveness
 * Seizures
 * Coma
 * Death

Labs/tests- Causes- Treatment- Interventions-
 * Serum sodium levels
 * Serum potassium
 * Serum osmolality
 * urine specific gravity and osmolality (2)
 * Cancer is the leading causeSome cancers produce ADH and some cause the brain to secrete ADH.
 * Most common with carcinoma of the lung
 * Tumors in the brain are also a leading cause of SIADH.
 * Pancreatic, duodenal and GU carcinomas
 * Thymoma
 * Hodgkin’s and Non-Hodgkin’s lymphoma
 * ===== Some cancers produce ADH and some cause the brain to secrete ADH. =====
 * ===== [[image:http://www.virtualmedicalcentre.com/uploads/VMC/DiseaseImages/600_SIADH.jpg caption="Syndrome of inappropriate antidiuretic hormone secretion; SIADH "]](3) =====
 * =====<span style="background-color: #ffffff; font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 120%;">Cancer drug may also cause SIADH (e.g. morphine sulfate, cyclophosphamide). =====
 * <span style="background-color: #ffffff; font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 120%;">Treat condition:
 * Maintain fluid restrictions (may be as low as 500-600ml/day)
 * Increase sodium intake
 * If tube feeing dilute feeding with saline (instead of plain water) and irrigate GI tubes with saline
 * If sodium becomes too low a hypertonic saline (3% NaCl) IV can be administered cautiously. Increased sodium may increase fluid overload and can cause heart failure.
 * <span style="background-color: #ffffff; font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 120%;">Drug therapy (demeclocycline an antibiotic which works in opposition to ADH)
 * <span style="background-color: #ffffff; font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 120%;">Treat cause:
 * Cancer therapy
 * Radiation
 * Chemotherapy
 * <span style="background-color: #ffffff; font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 120%;">Prevent fluid overload
 * Fluid restriction
 * Promote excretion of water
 * Monitor for s/s of fluid overload every 2 hours
 * Monitor I&O’s and weight patient. A 2 or more pound increase with a day is a reason for concern (Remember 1kg = 1L).
 * Keep mucous membranes moist with swabs or mouth rinse
 * Assess for diminishing deep tendon reflexes
 * Check vital signs for possible
 * Tachycardia
 * Hypothermia
 * Increased B/P (2)
 * Monitor response to therapy
 * Teach patient and family about fluid restrictions and drug therapy
 * Injury prevention/provide safe environment.
 * Check LOC every 1-4hrs depending on patient’s condition.
 * Seizure precautions.
 * Reduce environmental noises and lighting

<span style="background-color: #ffffff; font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 120%;"> 1. all content unless otherwise specified is from <span style="background-color: #ffffff; color: #262626; font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 120%;">Ignatavicius,, D., & Workman, L. (2010). //Medical-surgical nursing: patient-centered collaborative care//. St. Louis Mo.: Saunders. <span style="background-color: #ffffff; font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 120%;">2. []

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