Neuropeptide Biomarker Differentiates Ischemic Stroke

Plasma concentrations of precursor fragments of the neuropeptide enkephalin (proenkephalin A, or PENK-A) are elevated in patients with acute stroke, and are correlated with stroke severity and with brain lesion size, and they predicted mortality and more severe functional disability.

Scientists at the Center for Stroke Research (Berlin, Germany) measured plasma PENK-A and protachykinin A (PTA) concentrations in 189 consecutive patients who were admitted to hospital with symptoms of acute stroke. Midregional PENK-A 119–159 and N-terminal protachykinin A (PTA) were assessed by a newly developed chemoluminescence sandwich immunoassay, using a chemiluminescence platform and coated tube technique (Immunochemical Intelligence GmbH; Berlin, Germany).

Of 189 patients assessed, 65.6% presented with a stroke, 8.5% with a TIA, and 25.9% with a nonischemic event. The normal range of PENK-A is 41.8 to 131 pmol/L, and for PTA, the normal range is 30.8 to 179.2 pmol/L. The median level of PENK-A for the stroke patients was 123.8 pmol/L (range 93 - 160.5 pmol/L), while for TIA patients the median level was TIA 114.5 pmol/L (range 85.3 - 138.8 pmol/L). All the nonischemic event patients had PENK-A levels below 137.6 pmol/L. The PENK-A concentration increased in parallel to increasing severity of stroke. The PENK-A levels on admission in the 24 patients who subsequently died were significantly elevated compared to those of survivors.

Wolfram Doehner, MD, PhD, the senior author of the study, said, "Our data are intriguing and may help to advance the use of biomarkers in the clinical evaluation of stroke patients. There is clearly an unmet need to establish biomarker-guided prognostic and functional evaluations for patients with stroke. Unfortunately, we are severely running behind in the use of biomarkers for stroke evaluation compared to acute cardiac events." The study was published on July 16 2012 in the Journal of the American College of Cardiology.

Related Links:
Center for Stroke Research
Immunochemical Intelligence GmbH