BackgroundSecondary Raynaud’s phenomenon (RP) due to occupational exposure to hand-held vibrating tools is a well-recognized part of the Hand arm vibration syndrome (HAVS) [1]. Different pathophysiological mechanisms for HAVS-induced RP have been proposed, e.g., localized structural vascular and neuronal injuries as well as systemic inflammatory processes by increased oxidative stress [2-5]. Elevated plasma levels of thrombomodulin (TM), a marker for endothelial damage, have been shown in vibration-exposed workers [6, 7] with equal levels as in collagen diseases [7]. Von Willebrand factor (vWF) has been suggested as biomarkers for vibration induced RP [8]. Elevated levels of vWF have been found in RP patients who subsequently develop scleroderma or other connective tissue diseases, even in the absence of capillaroscopic abnormalities [9]. It is however still not clear whether the mechanisms for vibration related RP are similar to those for other forms of RP. Biomarkers for vascular injuries may shed light on this.ObjectivesTo investigate serum levels of TM and vWF in patients with HAVS, with or without RP.MethodsBlood samples were collected in the morning from 92 patients with HAVS. Forty-five (49%) of these had RP, 47 (51%) did not. Serum was removed and stored at -80 °C until analysis. TM and vWF were measured by using commercially available ELISA assays. Distributions were compared with Mann-Whitney U tests.ResultsHigher values of TM were found in HAVS patients with RP (median 6.1 ng/ml; range 2.7 – 30), compared to those without RP (5.2 ng/ml; 2.3 – 39; p = 0.02). Further higher levels of vWF were found in HAVS patients with RP (18 µg/ml; 6.2 – 33) compared to without RP (14 µg/ml; 6.9 – 34; p = 0.008).ConclusionAs in patients with RP due to connective tissue disorders higher levels of biomarkers for endothelial damage were shown in HAVS patients with RP. Increased serum levels of TM have been shown in previous studies on vibration injured patients [8, 9] but in one of the studies, no significant difference was shown between patients with RP and those without RP [9]. Our data indicates that RP symptoms is required to detect a significant change in the biomarker TM in vibration injured patients. Our data strengthen earlier findings that biomarkers of endothelial damage could be a useful tool in the assessment of vibrational induced injuries.