Effects of Oral Protein Load on Kidney Function in Patients Undergoing Cardiac Surgery

Inclusion Criteria:

1. Subjects older than 18 years undergoing elective cardiac surgery
2. Subjects older than 18 years with an estimated eGFR >60 ml/min/1.73 m2 (CKD-EPI)
3. Subjects who signed informed consent forms

Exclusion Criteria:

1. Pregnancy
2. Chronic kidney disease ≥ stage III (KDIGO criteria)
3. Preexisting acute kidney injury (as determined by all available serum creatinine values from hospital and outpatient medical records within the previous 90 days)
4. Solitary kidney
5. Diabetes mellitus type 1
6. Recent cardiac arrest or myocardial infarction up to 7 days before surgery
7. Liver failure or cirrhosis
8. Total parenteral nutrition
9. Haemoglobin <11 g/dl
10. Sepsis
11. History of malabsorption, chronic inflammatory bowel disease, short bowel, or pancreatic insufficiency
12. Transplant donor or recipient
13. Active autoimmune disease with renal involvement
14. Rhabdomyolysis
15. Prostate hypertrophy with International Prostate Symptom Score ≥20
16. Transcatheter aortic valve implantation
17. Active neoplasm
18. Patients who did not pause angiotensin-converting enzyme inhibitors or angiotensin II receptor blockers or received non-steroidal anti-inflammatory drugs a minimum of 48 hours before hospital admission.
19. Patients who received intravenous radiocontrast agents within the 72 hours before hospital admission.