indicated Normal glucose levels should not necessarily be used to exclude hypoglycemia as the seizure cause as secondary stress hyperglycemia may occur over time as the seizure progresses Hyponatremia is a relatively common cause of seizures in infants, so a bedside rapid sodium test should be performed A febrile seizure is defined as a seizure caused by a fever, but this is a diagnosis of exclusion While the formal definition of the International League Against Epilepsy considers age range for febrile seizures to be month to years, most of the published data and PEM approach are limited to those months to years of age Caution should be used in labeling someone as having a febrile seizure outside of this age range Other infectious etiologies that present with a fever and can be the direct cause of a seizure (e.g., meningitis) must first be ruled out clinically Routine performance of a lumbar puncture (LP) for patients with either simple or complex febrile seizure is not required (see Chapters 31 Fever and 94 Infectious Disease Emergencies ) but rather is based on clinical findings Furthermore, infections not involving the CNS may still be the cause of the seizure through the elaboration of fever and inflammatory mediators Presence of fever and/or an elevated white blood cell (WBC) count may direct one to look for a potential infectious cause, yet stress response with peripheral leukocytosis occurs in up to a quarter of children with generalized seizures Blood cultures should be limited to those patients at risk for bacteremia Urinalysis and chest radiographs can also be used to confirm a source of infection