Hyponatremia (low serum sodium) is one of the most common electrolyte disorders encountered in the ED. Most of the time this electrolyte disorder requires us to do less- not more. However, if the patient is critically ill from their hyponatremia then we need to know how to quickly intervene and even be a little creative if we don't have the medications that we want. We'll review how to do the right thing for these patients, track down the cause of hyponatremia, and make the right decisions so we don't cause any harm.