Value of serum prolactin in the management of syncope

A meta-analysis of studies of the usefulness of raised serum prolactin in diagnosing generalised tonic-clonic seizures (GTCS) in patients presenting to the accident and emergency (A&E) department after a single episode of syncope.

A three part question was defined. Medline, EMBASE, PubMed, the Cochrane Library were searched to identify relevant studies. Studies were evaluated for eligibility and quality and data extracted to calculate sensitivity (SN), specificity (SP), and likelihood ratios (LR).

Of 13 relevant studies only three met the criteria for evaluation. If a serum prolactin concentration is greater than three times the baseline when taken within one hour of syncope, then in the absence of test "modifiers": (1) the patient is nine times more likely to have suffered a GTCS as compared with a pseudoseizure positive LR = 8.92 (95% CI (1.31 to 60.91)), SN = 0.62 (95% CI (0.40 to 0.83)), SP = 0.89 (95% CI (0.60 to 0.98)) and (2) five times more likely to have suffered a GTCS as compared with non-convulsive syncope positive LR 4.60 (95% CI (1.25 to 16.90)), SN = 0.71 (95% CI (0.49 to 0.87)), SP = 0.85 (95% CI (0.55 to 0.98)).

A positive test result is highly predictive of a GTCS, however a negative test result does not necessarily exclude a seizure. Serum prolactin should be measured in patients presenting to the A&E department within an hour of a syncopal episode, unless the cause is immediately obvious.