Urinary TIMP‐2 and IGFBP‐7 protein levels as early predictors of acute kidney injury after cardiac surgery

Abstract

Background Acute kidney injury (AKI) is a frequent complication associated with on‐pump cardiac surgery. Early recognition may alter their prognosis. Therefore, the urinary concentrations of TIMP‐2 (tissue inhibitor of metalloproteinases‐2) and IGFBP7 (insulin‐like growth factor‐binding protein) as predictors for AKI were studied. Methods Repetitive blood and urine samples were collected consecutively from 50 patients. Demographic, intra‐, and postoperative data were recorded prospectively. To calculate the production of the TIMP‐2 and IGFBP‐7 protein concentrations, urinary samples were taken preoperatively, intraoperatively at 30 and 60 min after aortic clamping and at 0, 6, 12, and 24 h after admission to the intensive care unit (ICU). Results AKI occurred in 14 patients (28%), all of them at Kidney Disease: Improving Global Outcomes stage 1. Predictive value for [TIMP‐2] × [IGFBP7] was shown at 0 and 24 h after admission to ICU. At 0 h, the sensitivity was 84.6% and the specificity 55.6% for an ideal calculated cutoff at 0.07. After 24 h, the ideal cutoff amounted to 0.35 with a sensitivity of 53.8% and a specificity of 88.2%. The receiver operating characteristic curves demonstrated areas under the curve of 0.725 and 0.718. The suggested cutoffs of 0.3 and 2.0 could not be confirmed. The serum creatinine was reached to the peak median within 48 h after admission to ICU. Conclusion Postoperative risk assessment for the development of AKI can be established by [TIMP−2]×[IGFBP7]. Previously suggested cutoff values could not be confirmed. A correlation with urinary dilution parameters may enable the identification of more universal cutoffs.

Heart surgery and postoperative acute kidney injury

“…In this current study, authors 1 revealed that postoperative risk assessment for the development of AKI can be established by [TIMP-2] × [IGFBP -7]. Various biochemical markers have been investigated in studies and valuable results have been obtained.…”

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We read with great interest the article entitled "Urinary TIMP-2 and IGFBP-7 protein levels as early predictors of acute kidney injury after cardiac surgery." 1 We would like to congratulate the authors for their valuable contribution. However, we would like to discuss some points about acute kidney injury (AKI) occurring after heart surgery.

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Letter to the Editor: “Urinary TIMP-2 and IGFBP-7 protein levels as early predictors of acute kidney injury after cardiac surgery”.

“…To the Editor, The journal's article "Urinary TIMP-2 and IGFBP-7 protein levels as early predictors of acute kidney injury after cardiac surgery" piqued our attention. 1 It highlights the early identification of AKI after cardiac surgery based on a spike in urinary TIMP-2 and IGFBP-7 protein levels and links this with urinary dilution measurements. We agree that [TIMP2] [IGFBP7] can help determine postoperative AKI risk.…”

Urinary TIMP‐2 and IGFBP‐7 protein levels as early predictors of acute kidney injury after cardiac surgery

“…To the Editor, We read with great interest the paper "Urinary TIMP-2 and IGFBP-7 protein levels as early predictors of acute kidney injury after cardiac surgery" published in your prestigious journal. 1 It highlights early diagnosis of acute kidney injury (AKI) after cardiac surgery based on a rise in urinary tissue inhibitor of metalloproteinases 2 (TIMP-2) and insulin-like growth factor-binding protein 7 (IGFBP-7) levels and links this with urinary dilution measures. We concur with the finding that TIMP-2 and IGFBP-7 could aid in the postoperative assessment of AKI risk.…”