Serum prolactin in seizures from non-epileptic attacks

Q: What's the importance of serum prolactin in the differential diagnosis of seizures?

Answer: It may help in ruling in or out psychogenic nonepileptic seizures

Although prolactin is not a usual send-out test after seizures like lactate or creatine kinase (CK), it can be utilized if required to differentiate generalized tonic-clonic and focal seizures from psychogenic nonepileptic seizures. Although a low serum prolactin does not exclude an epileptic seizure, it lowers the likelihood of an epileptic seizure, even if it appears to be a generalized tonic-clonic seizure. 

Prolactin levels peak 15-20 minutes after the seizure and return to baseline within an hour. Ideally, the baseline prolactin level for comparison should be drawn approximately the same time the next day after the initial postictal serum prolactin measurement, and at least 6 hours after the last seizure. This recommendation is due to the circadian fluctuation of serum prolactin.

Caveats to prolactin level are pregnancy/lactation, prolactinomas, primary hypothyroidism, and dopamine antagonist drugs.

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References:

1. Chen DK, So YT, Fisher RS; Therapeutics and Technology Assessment Subcommittee of the American Academy of Neurology. Use of serum prolactin in diagnosing epileptic seizures: report of the Therapeutics and Technology Assessment Subcommittee of the American Academy of Neurology. Neurology. 2005 Sep 13;65(5):668-75. doi: 10.1212/01.wnl.0000178391.96957.d0. PMID: 16157897.

2. Shimmura M, Takase KI. Clinical utility of serum prolactin and lactate concentrations to differentiate epileptic seizures from non-epileptic attacks in the emergency room. Seizure. 2022 Feb;95:75-80. doi: 10.1016/j.seizure.2021.12.014. Epub 2022 Jan 5. PMID: 35016147.