Study of Urinary-Interleukin-18 (u-I L-18) as ans Early BioMarker of Post-Operative Acute Kidney Injury

Acute kidney injury (AKI) is commonly seen in the perioperative period and in the intensive care unit (ICU) and is associated with a prolonged hospital stay and high morbidity and mortality (1). IL-18 is a pro-inflammatory cytokine and has been shown to be involved in mediating inflammation in many organs (2,3). Renal IL-18 mRNA levels are significantly up-regulated in the proximal tubules following ischemia-reperfusion injury, autoimmune nephritis, and cisplatin-induced nephrotoxicity (4). Forty patients were selected from different surgical departments and intensive care unit, Menofia University Hospital, and informed consents were obtained from all patients. This study was approved ethically by the local authority of the hospital and the patients were consented to do this study. Two groups of patients: Group 1: included 15 patients who were underwent cardiothoracic surgery. Group 2: included 25 patients who were underwent non cardiothoracic surgery. The selected patients were subjected to: Pre-operatively: history taking, full clinical examination, laboratory investigations as blood urea and serum creatinine, CBC, serum albumin, serum sodium, serum potassium, ALT, AST, prothrombin time and concentration and urine analysis and estimated glomerular filtration rate (eGFR). Intra-operatively: the duration of the operation, Volume depletion and the need for transfusion of blood or blood constituents. Post-operatively: Samples were collected after 24 and 48 hrs. postoperatively for determination of: Serum Creatinine, BUN, Serum sodium and potassium levels and arterial blood gases (ABG). Urinary IL-18 measured in the first 24 hrs. and after 24 hrs. Urine output during the first 48 hrs. postoperatively also was measured. After that; the patients were observed for 3 days for the need for further management according to the outcome of the acute insult. Our patients were classified into 2 major groups according to Risk, Injury, Failure, Loss, and End- stage Kidney (RIFLE) classification of AKI: RIFLE group who met the RIFLE criteria of Acute Kidney Injury Network (AKIN) and Non RIFLE group who did not meet the RIFLE criteria or did not had AKI. Urinary IL-18 level was significantly increased in RIFLE positive group than in RIFLE negative group and also was early than elevation of serum creatinine by two to three days. So, urinary IL-18 showed specificity as a biomarker for post-operative AKI. Preoperative anemia, prolonged operative duration, massive intraoperative blood loss and intraoperative volume depletion were significant risk factors for development of postoperative acute kidney injury.