Ronald Brisman, M.D.
Low sodium in the blood is often defined as less than 135 mEq/L. It is severe if it is less than 128 mEq/L.back to top
If hyponatremia is mild, there may be no symptoms. As it becomes more severe, there may be lethargy, loss of appetite, nausea and vomiting, difficulty concentrating, agitation, headaches, seizures or even loss of consciousness. More severe symptoms are associated with lower levels of sodium in the blood and with greater speed with which it develops.back to top
In patients with trigeminal neuralgia, medications such as oxcarbazepine (Trileptal) can cause patients to secrete a hormone (anti-diuretic hormone), which causes them to retain water and dilute (lower) the concentration of sodium in their blood. Oxcarbazepine and carbamazepine (Tegretol) can cause hyponatremia, but it is more common with oxcarbazepine. Factors that increase the likelihood that oxcarbazepine or carbamazepine will cause hyponatremia include large amounts of fluids (either orally or intravenously), or the concurrent use of diuretics or levetiracetam (another anti-seizure medicine). There are many other medicines that have been associated with hyponatremia including selective serotonin reuptake inhibitors (SSRIs) such as fluoxetine (Prozac), sertraline (Zoloft) and paroxetine (Paxil). Hypothyroidism is one of many medical conditions that can cause hyponatremia.back to top
Treatment of symptomatic hyponatremia may require restriction of fluid intake and sometimes added sodium. To prevent hyponatremia, it is important to avoid excessive amounts of fluids. Blood levels of sodium need to be monitored. Patients who have an initial low sodium value after starting oxcarbazepine or carbamazepine are more likely to run into a subsequent problem from hyponatremia. Be particularly careful to check more frequently patients who are taking diuretics, the anti-seizure medicine levetiracetam or selective serotonin reuptake inhibitors. If the patient is showing a tendency to hyponatremia, try to use as small a dose of oxcarbazepine or carbamazepine as possible and consider switching from oxcarbazepine to carbamazepine or, if possible, to some other anti-trigeminal neuralgia medication. Patients with recurrent significant hyponatremia are more likely to need a neurosurgical procedure to help control their trigeminal neuralgia and lessen the need for medications.back to top