What additional emergency department work‑up is indicated for a seizure patient with recent antiepileptic dose reduction, missed neurology injection, anxiety/migraine triggers, after ordering CT head, CBC, CMP, urinalysis, urine drug screen, and urine pregnancy test?

Additional Emergency Department Workup

Your current workup is comprehensive and covers the essential testing; the only additional test to strongly consider is an antiepileptic drug (AED) level, given her recent dose reduction and the fact that she is on chronic therapy. 1

Antiepileptic Drug Level

• Check a serum level of her current AED (likely levetiracetam, valproate, or another agent given the 1000 mg BID dosing that was reduced to 500 mg BID). 1
• The abrupt 50% dose reduction three days ago is a clear precipitant for breakthrough seizures in a patient with known epilepsy. 1
• Subtherapeutic levels will confirm that the dose reduction triggered this event and guide whether to reload or adjust dosing. 1
• This is particularly important because she also missed her long-acting injectable medication (14 months versus the usual 7-month interval), creating a dual medication gap. 1

Serum Prolactin Level

• Consider drawing a serum prolactin level 10–20 minutes post-seizure if there is any doubt about whether this was a true epileptic seizure versus a psychogenic non-epileptic event, especially given her high anxiety and stress. 2
• Elevated prolactin helps differentiate generalized tonic-clonic or focal seizures from psychogenic seizures, though the 10-minute witnessed seizure with no post-ictal state is atypical for a generalized tonic-clonic seizure. 2
• However, if she arrived after the 20-minute window, this test loses its diagnostic value. 2

Magnesium Level

• Add a magnesium level to your metabolic panel if not already included in your CMP, particularly if there is any history of alcohol use, malnutrition, or diuretic use. 3
• Hypomagnesemia is a common and reversible cause of seizures. 3

Rationale for Your Current Workup

Your ordered tests appropriately address the key diagnostic priorities:

• Glucose and sodium are the only routine labs that consistently alter acute ED management and are mandatory. 4, 1, 3
• Pregnancy test is essential for any woman of childbearing age, as it affects imaging decisions, disposition, and AED selection. 4, 3
• CT head is indicated because she has a known seizure disorder with breakthrough activity, and you need to exclude acute structural causes (hemorrhage, mass effect, stroke). 4, 1
• CBC and CMP help identify infection, electrolyte disturbances, renal dysfunction, or hepatic issues that could lower seizure threshold. 4, 3
• Urinalysis screens for infection, which can precipitate seizures. 3
• Urine drug screen is appropriate given the clinical context of stress and the need to exclude toxic or withdrawal precipitants. 4, 3

What You Do NOT Need

• Lumbar puncture is not indicated unless she develops fever, meningeal signs, persistent altered mental status, or is immunocompromised. 4, 1, 3
• Emergent EEG is not needed because she is not post-ictal on arrival and has returned to baseline; EEG is reserved for suspected non-convulsive status epilepticus or unexplained persistent altered consciousness. 1, 5
• Expanded electrolyte panel (calcium, phosphate) is only necessary if she has known renal disease, malnutrition, or is on diuretics—none of which you mention. 3

Disposition and Next Steps

• She can be safely discharged if her CT is normal, labs show no acute abnormalities, and she remains at neurological baseline, given that she has an appointment with her neurologist tomorrow. 1
• More than 85% of early recurrent seizures occur within 6 hours of the index event, so if she remains stable during her ED stay, recurrence risk is low. 1
• Do not restart or adjust her AED in the ED—defer this decision to her neurologist tomorrow, who can coordinate the dose adjustment and address the missed long-acting injection. 1
• Provide safety counseling: no driving, avoid swimming alone, avoid heights, and ensure she has supervision until she sees neurology. 1

Common Pitfalls to Avoid

• Do not miss the medication non-adherence or dose change as the precipitant—this is a provoked seizure due to subtherapeutic AED levels, not a new-onset event requiring extensive workup. 1
• Do not assume anxiety or migraine alone caused the seizure—while they may lower seizure threshold, the primary issue is inadequate AED coverage. 1
• Do not delay checking the AED level—this is the single most actionable test you can add to your current workup. 1