seizure or not: is prolactin useful?

11 Jan

–200 patients with seizure-like activity, 109 ultimately diagnosed with seizure
–31% (of 200 patients) had abnormal prolactin (upper limit of normal ~30mg/dL)

–the numbers:

  • sensitivity of this serum prolactin was 42%
  • specificity was 82%
  • positive predictive value (PPV) of 74%
  • negative predictive value (NPV) of 54%
  • overall accuracy of 60% in the diagnosis of seizure,
  • likelihood ratio of 2.4

–their conclusion: “The measurement of serum prolactin is helpful as a confirmatory test, but not as screening test in the emergency department setting.”

–most studies used 2x baseline serum prolactin level as ‘elevated’
–the numbers:

  • pooled sensitivity for generalized tonic-clonic seizures (60.0%); for complex partial seizures (46.1%)
  • pooled specificity was similar for both (approximately 96%)
  • 2 Class II studies were consistent in showing prolactin elevation after tilt-test-induced syncope.

–their conclusion: “Elevated serum prolactin assay, when measured in the appropriate clinical setting at 10 to 20 minutes after a suspected event, is a useful adjunct for the differentiation of generalized tonic-clonic or complex partial seizure from psychogenic nonepileptic seizure among adults and older children (Level B). Serum prolactin assay does not distinguish epileptic seizures from syncope (Level B)”

–usefulness of raised serum prolactin in diagnosing generalised tonic-clonic seizures (GTSC) in patients presenting to the ED after a single episode of syncope
–13 relevant studies only 3 met the criteria for evaluation

–the numbers: if a serum prolactin concentration is > 3x the baseline when taken within one hour of syncope, then…

  • LR (likelihood ratio) of GTSC vs pseudoseizure = 8.92, sensitivity 0.62, specificity 0.89
  • LR of GTSC vs. syncope = 4.60, sensitivity 0.71, specificity 0.85

–serum prolactin in seizure: not too useful in the ED
–generally poor sensitivity, better specificity, but only if tested early (~10-60 min s/p episode)

–so if you can draw it fast, and if its significantly elevated, it might be useful (a lot of if’s), but if its low, doesn’t mean it’s not a seizure

serum prolactin in seizure: not too useful in the ED

Reference(s): study, review, meta-analysis, picture


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