TTR and chronic kidney disease: The univariate analysis showed that there were statistically significant differences between the two groups in terms of chronic kidney disease history, nutritional indicators (total protein, prealbumin, creatinine, red blood cells, lymphocytes, hemoglobin), intestinal barrier function indicators (DAO, D-lactate), operation type, operation duration, and stay in the ICU (p < 0.05, see Table 3).