Endocan is a stable circulating molecule in ICU patients

Background: Endocan is a lung endothelial cell secreted proteoglycan, possessing multiple physiological roles and potential therapeutic and diagnostic utility as biomarker in pneumonia and acute respiratory distress syndrome. Endocan synthesis and secretion can be induced by proinflammatory cytokines such as TNF-α, but can also be subject of proteolytic degradation causing preanalytical variation.

Methods: We investigated the stability of endocan in conventional serum, plasma, anticoagulated whole blood, as well as whole blood and plasma stabilized with protease inhibitors.

Results: Among the recipient tubes for blood collection, those with EDTA gave minimal interference. No dilution effect was observed on recovery tests from 1:2 to 1:16 (v:v). The recovery test in 10 plasma EDTA samples from healthy subjects or septic patients indicated a median recovery of 104.5% [104%-107.5%], and 97% [88.5%; 102.5%], respectively. Patient's plasma endocan remains stable when stored at room temperature till 72h, or following 3 freeze thaw cycles. Finally, no interference was observed with hemolytic, icteric or turbidic plasma samples.

Conclusion: These results are consistent with the view that endocan measured in ICU patients is intact, stable, and accurate. Then, the low endocan level observed in ICU patients who developed ARDS is likely to be reliable.