Clinical utility of serum prolactin and lactate concentrations to differentiate epileptic seizures from non-epileptic attacks in the emergency room.

PURPOSE: To evaluate the diagnostic utility of serum prolactin (PRL) and lactate (LAC) concentrations for patients presenting with either or both convulsions and transient loss of consciousness (TLOC) in the emergency room (ER).

METHODS: This was a retrospective single-center study conducted in a tertiary care hospital ER. Medical records of consecutive patients who presented with convulsions or TLOC between January 2018 and December 2020 were reviewed. Patients with an ER diagnosis of epileptic seizures, psychogenic non-epileptic seizure (PNES), and syncope were selected for analysis. Serum PRL and LAC concentrations were measured within 3 h of the event and compared between groups.

RESULTS: Among the 440 eligible patients, 173 (39.3%) were included for analysis. Serum PRL concentration was significantly higher in patients with epileptic seizures with convulsions than in those with PNES with convulsions (p < 0.001) and convulsive syncope (p = 0.023). Serum LAC concentration was not significantly elevated in patients with convulsive syncope. Using a PRL cut-off value of 24.0 ng/mL, serum PRL concentration had 100.0% sensitivity and 82.9% specificity for differentiating between PNES and other attacks without convulsions.

CONCLUSION: Elevated serum PRL with normal serum LAC concentration in patients who have attacks with convulsions suggests convulsive syncope. Serum PRL concentration is useful in the diagnosis of PNES with convulsions. However, serum LAC concentration is not useful as a routine screening test for attacks without convulsions in the ER.