What is SIADH?

Dear Ask The Doctor: The doctors said they think my 84 year old mom has SAIDH which causes her sodium level to drop. How is this diagnosed and what is the treatment.

Dear Audrey: SIADH or the syndrome of inappropriate anti-diuretic hormone (ADH) secretion is a common cause of low blood sodium in a hospitalized patient that is fluid overloaded. It may be caused by certain drugs, head injury or subarachnoid haemorrhage, infections including; pneumonia, meningitis, lung or brain abscess, small cell lung cancer, or lymphoma. In normal circumstances if a patient is fluid overloaded with a low sodium level, they will excrete the excess fluid, and the sodium level will return to normal. But in SIADH the hormone ADH is released inappropriately causing more fluid retention, further diluting the low sodium level and aggravating the situation. It is diagnosed by measurement of a low plasma sodium level and a low plasma osmolality level. Treatment is by treating the underlying cause and fluid restriction of the patient.