Monitoring urinary orosomucoid in patients undergoing cardiac surgery: A promising novel inflammatory marker

Background: Urinary biomarkers might provide non-invasive tool for monitoring of systemic processes. We aimed to investigate the time-course of urinary orosomucoid (u-ORM) excretion after cardiac surgery hypothesizing that u-ORM is an early and sensitive marker of systemic inflammatory activation.

Methods: During a 5-day follow-up study we monitored u-ORM levels in cardiovascular patients who underwent on-pump cardiac surgery (n=38). The patients baseline data were compared to healthy control individuals (n=40). u-ORM was measured by a newly developed automated turbidimetric assay and values were referred to urinary creatinine and expressed as u-ORM/u-CREAT (mg/mmol).

Results: The cardiovascular patients showed slightly increased baseline u-ORM excretion compared to healthy controls (0.29 vs 0.08mg/mmol, p<0.001). After cardiac surgery, a rapid 10-fold elevation in u-ORM/u-CREAT levels was found. The values remained high till the 3rd postoperative day, and they then decreased significantly (p<0.01) on the 5th day after surgery. u-ORM/u-CREAT mirrored well the perioperative tendency of hs-CRP levels, but it did not follow the non-decreasing kinetics of serum ORM concentrations during the follow-up. u-ORM/u-CREAT correlated significantly (p<0.001) with inflammatory parameters (hs-CRP, se-ORM, WBC).

Conclusions: We described u-ORM as an early and sensitive marker of inflammatory activation. The rapid elevation of u-ORM/u-CREAT after surgery and its postoperative kinetics could reflect the magnitude of inflammatory response better than serum ORM and similar to hs-CRP. u-ORM measurements might provide a novel non-invasive tool for real-time monitoring of systemic inflammation, however further investigations are required to confirm it.