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Published on: February 16, 2016
Evaluation of cystatin C with iohexol clearance in cardiac surgery
B Brondén1, A Eyjolfsson, S Blomquist
1Department of Anaesthesia and Intensive Care, Lund University, Sweden. bjornbronden@hotmail.com
Insights
Plasma cystatin C offers a more accurate assessment of kidney function after cardiac surgery compared to creatinine. This study found cystatin C clearance estimations closely matched the reference iohexol clearance method.
Area of Science:
- Nephrology
- Cardiology
- Biomarkers
Background:
- Post-operative renal dysfunction is a significant complication following cardiac surgery.
- Accurate monitoring of renal function is crucial for patient outcomes.
- Plasma cystatin C is a sensitive marker for glomerular filtration rate (GFR), but its utility in cardiac surgery requires further evaluation.
Purpose of the Study:
- To evaluate the diagnostic accuracy of plasma cystatin C for determining GFR in cardiac surgery patients.
- To compare the accuracy of cystatin C clearance with creatinine clearance against iohexol clearance, a reference standard.
Main Methods:
- Prospective enrollment of 21 patients undergoing elective coronary artery bypass grafting.
- Iohexol clearance measurements performed pre-operatively and on post-operative day 2.
- Plasma cystatin C, creatinine, and C-reactive protein levels measured serially post-surgery.
- Estimated creatinine and cystatin C clearances calculated and compared to iohexol clearance.
Main Results:
- Plasma cystatin C and its reciprocal showed strong correlations with iohexol clearance (r=-0.90 and 0.86).
- Creatinine and its reciprocal also correlated with iohexol clearance (r=-0.83 and 0.78).
- Estimated cystatin C clearance did not significantly differ from iohexol clearance (P=0.81), unlike estimated creatinine clearance (P<0.01).
Conclusions:
- Cystatin C-based GFR estimations are more accurate than creatinine-based estimations in the context of cardiac surgery.
- Plasma cystatin C demonstrates a stronger correlation with iohexol clearance compared to creatinine in this patient population.
Background:
Post-operative renal dysfunction after cardiac surgery is not uncommon and can lead to adverse outcome. The ability to accurately monitor renal function is therefore important. Cystatin C is known to be a sensitive marker of the glomerular filtration rate (GFR), but it has not been fully evaluated in cardiac surgery. Iohexol clearance is considered a reliable reference method for the determination of GFR. The aim of this study is to, for the first time, evaluate the diagnostic accuracy of plasma cystatin C compared with iohexol clearance in cardiac surgery.
Methods:
Twenty-one patients scheduled for elective coronary artery bypass grafting were prospectively enrolled in the study. Before surgery and on the second post-operative day, an iohexol clearance was performed. Plasma cystatin C, plasma creatinine and plasma C-reactive protein were determined before surgery and on the first, second, third and fifth post-operative day. Estimated creatinine and cystatin C clearances were determined.
Results:
Post-operative cystatin C and 1/cystatin C correlated strongly to iohexol clearance (r=-0.90 and 0.86) and so did creatinine and 1/creatinine (r=-0.83 and 0.78). Estimated creatinine clearance differed from iohexol clearance (P<0.01), whereas estimated cystatin C clearance did not differ from iohexol clearance (P=0.81). No correlation was found between C-reactive protein and cystatin C.
Conclusion:
This study indicates that clearance estimations based on cystatin C are more accurate compared with estimations based on creatinine in determining GFR in cardiac surgery. Cystatin C has, in this study population, a stronger correlation to iohexol clearance than creatinine.
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