Initial Laboratory Orders for Older Adults with New-Onset Seizures

Core Laboratory Tests

The American College of Emergency Physicians recommends serum glucose and sodium tests for all adult patients with seizures, as these are the most common metabolic abnormalities associated with seizures 1
A complete blood count (CBC) is recommended to evaluate for infection or other hematologic abnormalities in patients with new-onset seizures 2
A basic metabolic panel, including BUN, creatinine, and electrolytes, is recommended for patients with new-onset seizures 2, 1
Calcium and magnesium levels should be checked, especially in older adults who may be taking medications that affect these electrolytes 2, 1
A pregnancy test is recommended for women of childbearing age with new-onset seizures 1

A drug screen should be considered in patients with first-time seizures, particularly if there is suspicion of substance use 1
An extended electrolyte panel, including phosphate, is recommended for patients with known renal insufficiency, malnutrition, or those taking diuretics 1
Toxicology screening is recommended if medication toxicity is suspected in patients with new-onset seizures 3

A head CT scan is recommended for all older adults with new-onset seizures to evaluate for structural lesions 2, 1
An MRI is preferred if available, particularly for patients with focal neurological deficits or when CT is negative but clinical suspicion for structural abnormality remains high 1

Magnesium levels should be checked in patients with suspected alcohol-related seizures, as hypomagnesemia is common in this population 1
Lumbar puncture should be considered in immunocompromised patients, those with fever, or signs of meningeal irritation after head CT 1

Alcohol withdrawal seizures should be a diagnosis of exclusion, especially in first-time seizures in older adults 1, 3
Laboratory testing has a relatively low yield in patients who have returned to baseline neurological status, with most abnormalities predictable by history and physical examination 1
Studies have found very few cases of unsuspected metabolic abnormalities, with one prospective study finding only 1 unexpected case of hypoglycemia in 163 patients 1

Abnormal neurological examination or focal deficits require more extensive evaluation in patients with new-onset seizures 3
Fever or signs of infection require more extensive evaluation in patients with new-onset seizures 3
Immunocompromised status requires more extensive evaluation in patients with new-onset seizures 1