Hyponatremia is associated with an increased risk of death. The economic costs of hyponatremia are estimated at $2.6 billion in the United States. Signs and symptoms of hyponatremia include nausea and vomiting, headache, short-term memory loss, confusion, lethargy, fatigue, loss of appetite, irritability, muscle weakness, spasms or cramps, seizures, and decreased consciousness or coma. The presence and severity of signs and symptoms are related to the level of salt in the blood, with lower levels of plasma sodium associated with more severe symptoms. However, emerging data suggest that mild hyponatremia (plasma sodium levels at 131–135 mmol/L) is associated with numerous complications
Hypotonic hyponatremia a side effect of certain medicines, lung problems such as pneumonia or abscess, brain disease, or certain cancers (most often small cell lung carcinoma). The cornerstone of therapy for SIADH is reduction of water intake. If hyponatremia persists, then demeclocycline (an antibiotic with the side effect of inhibiting ADH) can be used. SIADH can also be treated with specific antagonists of the ADH receptors, such as conivaptan or tolvaptan. Another cause is psychogenic polydipsia. A third group of people with hyponatremia are often said to be "hypervolemic". They are identified by the presence of peripheral edema. In fact, the term