What laboratory tests should be ordered for a 22-year-old woman with postural orthostatic tachycardia syndrome presenting to the emergency department with an active seizure that required two 5 mg doses of midazolam (Versed) to stop?

Laboratory Workup for Status Epilepticus in a 22-Year-Old with POTS

Order immediate bedside glucose, followed by comprehensive metabolic panel (sodium, potassium, calcium, magnesium, BUN, creatinine), complete blood count, pregnancy test, and toxicology screen. 1, 2, 3

Immediate Point-of-Care Testing

• Check bedside finger-stick glucose immediately – hypoglycemia is one of the most common treatable causes of seizures and requires urgent correction. 1, 2, 3

Essential Laboratory Panel

Metabolic Studies (Priority)

• Serum glucose and sodium are mandatory – these are the only two laboratory abnormalities that consistently alter acute ED management and represent the most frequent correctable metabolic causes of seizures. 1, 2, 3

• Complete metabolic panel including calcium and magnesium – while the guidelines emphasize glucose and sodium as highest yield, a basic metabolic panel is essential in status epilepticus to evaluate for multiple electrolyte disturbances, renal function, and acid-base status. 1, 2

• Calcium levels are particularly important given that this patient required two doses of benzodiazepines to terminate seizure activity, suggesting potential underlying metabolic derangement. 2

• Magnesium levels should be checked as hypomagnesemia can both cause and perpetuate seizure activity. 4, 2

Hematologic Studies

• Complete blood count (CBC) – evaluate for infection, anemia, or hematologic abnormalities that may trigger or complicate status epilepticus. 1

Reproductive Health

• Pregnancy test is mandatory for this 22-year-old woman of childbearing age, as pregnancy affects testing decisions, disposition, and antiepileptic drug selection. 2, 3

Toxicology

• Toxicology screening should be performed given the first-time presentation and to evaluate for substance use, withdrawal, or medication overdose as potential seizure triggers. 1, 2

Additional Testing Based on Clinical Context

Arterial Blood Gas

• Consider arterial blood gas if respiratory compromise is present or if there is concern for metabolic acidosis following prolonged seizure activity requiring two doses of midazolam. 1

Lumbar Puncture Considerations

• Lumbar puncture is NOT routinely indicated for uncomplicated first-time seizures. 2, 3

• However, strongly consider LP after head CT if this patient has fever, persistent altered mental status beyond expected post-ictal period, or any immunocompromised features, as CNS infection must be excluded in status epilepticus. 1, 3

Critical Pitfalls to Avoid

• Do not assume POTS explains the seizure – POTS itself does not cause seizures, though one case report describes their coexistence. 5 This is a new-onset seizure requiring full workup regardless of her POTS history.

• Do not delay glucose correction – if hypoglycemia is identified on finger-stick, treat immediately before waiting for confirmatory serum levels. 1, 3

• Do not overlook hyponatremia – it can both cause seizures and result from prolonged seizure activity, requiring prompt but cautious correction. 1, 2

• Do not miss subtle status epilepticus – if she has not returned to baseline neurologic function, emergent EEG should be performed to evaluate for nonconvulsive status epilepticus. 1, 3

Neuroimaging Considerations

• Emergent non-contrast head CT is indicated given that she required two doses of benzodiazepines (suggesting difficult-to-control seizure), has never been seen in the ER before (first documented seizure), and to exclude structural lesions before any potential lumbar puncture. 3