Abstract: Objective To explore the effects of citric acid on patients with severe burn complicated with acute renal injury treated by continuous renal replacement therapy (CRRT). Methods Medical records of 83 patients with large area of burn complicated with acute renal injury admitted to intensive care unit (ICU) of our department from January 2015 to December 2018 and meeting the inclusion criteria were analyzed retrospectively. The patients were divided into heparin group [n=43, 25 males and 18 females, aged (35.0±2.5) years] and citric acid group [n=40, 22 males and 18 females, aged (37.0±6.6) years] according to different anticoagulation methods. After admission, routine support treatment and CRRT were performed after being diagnosed with acute renal injury in patients in 2 groups. Patients in heparin group were treated with low molecular weight heparin for anticoagulation with first dosage of 20 U/kg and an increase of 2.5 to 5.0 U per hour, and patients in citric acid group were given citric acid of 0.02 g/mL with dosage of 150~200 mL/h for anticoagulation. The use time of blood filter, recovery time of urine volume, and time of staying in ICU, and platelet count, activated partial thromboplastin time (APTT), prothrombin time (PT), and serum creatinine, urea nitrogen, cystatin C, procalcitonin, C-reactive protein, and neutrophil, leukocyte count, blood sugar, aspartate aminotransferase (AST), alanine aminotransferase (ALT), and heart rate, body temperature, and mean arterial pressure before treatment and post treatment hour (PTH) 24 were recorded. Besides, occurrence of hemorrhage, hypocalcemia, metabolic acidosis, metabolic alkalosis, and death within 28 days post injury were recorded. Data were processed with t test and chi-square test. Results The use time of blood filter of patients in citric acid group was (28.7±3.2)h, significantly longer than (19.4±2.6) h in heparin group (t=14.139, P<0.01). The recovery time of urine volume and time of staying in ICU of patients in citric acid group were respectively (7.6±0.9) and (9.6±1.3) d, significantly shorter than (9.2±1.5) and (11.2±1.8) d in heparin group (t=5.516, 4.697, P<0.01). Before treatment, there were no statistically significant differences in platelet count, APTT, and PT of patients in 2 groups (t=1.235, 0.515, 1.279, P>0.05). At PTH 24, the platelet count of patients in citric acid group was significantly higher than that in heparin group (t=10.947, P<0.01), and APTT and PT of patients in citric acid group were significantly shorter than those in heparin group (t=7.069, 9.142, P<0.01). Before treatment, there were no statistically significant differences in serum creatinine, urea nitrogen, and cystatin C of patients in 2 groups (t=1.684, 1.878, 1.472, P>0.05). At PTH 24, the serum creatinine, urea nitrogen, and cystatin C of patients in citric acid group were significantly lower than those in heparin group (t=7.778, 9.776, 5.117, P<0.01). Before treatment, there were no statistically significant differences in serum procalcitonin and C-reactive protein of patients in 2 groups (t=1.413, 0.898, P>0.05). At PTH 24, the serum procalcitonin and C-reactive protein of patients in citric acid group were significantly lower than those in heparin group (t=2.635, 2.297, P<0.05). Before treatment, there were no statistically significant differences in neutrophil, leukocyte count, blood sugar, AST, and ALT of patients in 2 groups (t=0.555, 0.816, 0.470, 1.896, 0.982, P>0.05). At PTH 24, the neutrophil, leukocyte count, blood sugar, AST, and ALT of patients in citric acid group were significantly lower than those in heparin group (t=2.054, 3.314, 7.185, 2.151, 3.013, P<0.05 or P<0.01). Before treatment, there were no statistically significant differences in heart rate, body temperature, and mean arterial pressure of patients in 2 groups (t=1.406, 0.474, 0.720, P>0.05). At PTH 24, the heart rate, body temperature, and mean arterial pressure of patients in citric acid group were significantly lower than those in heparin group (t=2.307, 4.498, 2.056, P<0.05 or P<0.01). The incidence of hemorrhage of patients in citric acid group while in hospital was significantly lower than that in heparin group (χ²=4.949, P<0.05). There were no statistically significant differences in incidence of hypocalcemia, metabolic acidosis, metabolic alkalosis, and death rate within 28 days post injury of patients in 2 groups while in hospital (χ²=3.346, 0.884, 0.297, 0.324, P>0.05). Conclusions Citric acid has significant anticoagulant effect on patients with large area of burn complicated with acute renal injury treated by CRRT, which can prolong the use time of the blood filter, shorten the recovery time of urine volume and time of staying in ICU, improve renal function indexes, blood biochemical indexes, and inflammation indexes, maintain the stability of internal environment, and reduce the risk of hemorrhage.