Serum free hemoglobin as a novel potential biomarker for acute ischemic stroke

Currently, no practical biomarker is available for the diagnosis of acute ischemic stroke. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) has being applied extensively to analyze large biomolecules such as proteins. The technique is likely to be of remarkable value as indicators of systemic processes such as atherosclerosis and stroke. The aim of this study is to identify potential protein biomarkers for ischemic stroke diagnosis utilizing MALDITOF MS. Serum samples obtained from acute ischemic stroke patients (n = 47) and controls (n = 34) were analyzed by MALDI-TOF MS. Stroke severity was assessed by the National Institutes of Health Stroke Scale (NIHSS), subtype by the Trial of Org 10172 in Acute Stroke Treatment (TOAST), functional outcome by the modified Rankin Scale (mRS) and infarct volume by the diffusion-weighted images. Risk factors and routine laboratory data of the stroke patients were registered prospectively. The peaks of hemoglobin (Hb) alpha-chain and beta-chain were differentially expressed between stroke patients and controls (p < 0.0001). Hb ions were detected in the samples collected from 33 (70.2 %) stroke patients and 5 (14.7 %) controls. The sensitivity is 70.2 % and the specificity is 85.3 %. Among stroke patients, there is no significant correlation (p > 0.05) between Hb peaks and the NIHSS, TOAST, mRS, stroke risk factors, infarct volume, infarct location and laboratory data. Serum free Hb may serve as a novel potential biomarker for the diagnosis of acute ischemic stroke. The clinical value of this potential biomarker may be clarified by further studies quantifying serum free Hb levels.