User:Mr. Ibrahem/Syndrome of inappropriate antidiuretic hormone secretion

Syndrome of inappropriate antidiuretic hormone secretion (SIADH) occurs when excessive amounts of antidiuretic hormone (ADH) resulting in water retention and low sodium. Symptoms may vary from none to confusion, decreased level of consciousness, muscle twitching, and seizures.

It may be caused by central nervous system diseases, cancer, medications, lung disorders, inherited mutations, and certain hormone deficiencies. Brief episodes may occur as a result of pain or stress. Diagnosis is based on a serum sodium of less than 135 mEq/L, serum osmolality less than 275 mOsm/kg, urine sodium of more than 40 mEq/L, urine osmolality of greater than 100 mOsm/kg, and normal blood volume in the absence of other possible causes.

Treatment may include restriction of fluid intake, correction of the underlying cause, and medications to block the effects of ADH on the kidneys. Other measures may include salt tablets, intravenous saline, or furosemide. Hypertonic saline may be used if severe symptoms are present; however, sodium levels should not be increased more than 8 mEq/L per 24 hours.

SIADH occurs commonly among older people and those in hospital. It becomes more common with age. It was originally described in 1957 by William Schwartz and Frederic Bartter in two people with small-cell lung cancer. They also described the criteria that are still used as of 2020 to diagnose the condition.