Dilutional hyponatremia is a disorder of fluid and electrolyte balance caused by excessive release of antidiuretic hormone ( ADH ).
Alternative Names
Syndrome of inappropriate antidiuretic hormone secretion; SIADH
Causes, incidence, and risk factors
Fluid and electrolyte imbalance in this syndrome result from the inability to excrete dilute urine, retention of water within the body, and low sodium levels. The most common cause of SIADH is a type of lung cancer called "oat cell" or small cell, which secretes excessive ADH . Other causes are pancreatic cancer , prostate cancer , Hodgkin's disease , central nervous system disorders, pulmonary disorders, certain drugs, thymomas, myxedema , and psychosis . SIADH may also develop in some children during the acute phase of meningitis . Risk factors are related to the causes.
Treatment
The goal of treatment is to restrict fluid intake to one-half or one liter of fluid per day. The cause of the disorder must be treated, especially in the case of malignancy where radiation, chemotherapy , or surgical removal of the tumor may correct the water retention.
Expectations (prognosis)
The outcome is related to the underlying disease.
Prevention
Prompt treatment of causative conditions may be helpful.