The significance of plasma fibroblast growth factor 23 in predicting acute renal injury in rats

Objective To investigate the value of FGF23 in early prediction of acute kidney injury (AKI) in rats. Methods (1) Establishment of AKI model in rats:Twenty male SD rats were randomly divided into normal control group and folic acid (FA) modeling group with 10 rats in each group. Normal control group:A single dose of 0.15 M NaHCO₃ solution was injected intraperitoneally. FA modeling group:A single dose of FA solution was injected intraperitoneally. For all the rats, their blood specimens were collected at 0 h and 48 h respectively for detection of serum creatinine and urea nitrogen. (2) Collection of blood and urine specimens and detection at 8 time points:Eighty male SD rats were randomly divided into8 groups with 10 rats for each group, 0 h, 1 h, 2 h, 4 h, 8 h, 12 h,24 h and 48 h groups, respectively, with each group corresponding to one time point. The o h group was the normal control group, the other 7 groups were experimental. Blood and urine specimens were collected at corresponding time points, respectively. Serum creatinine (Scr), blood urea nitrogen(BUN), plasm fibroblast growth factor 23 and renal injury molecule-1 contents were determined. Results (1) Scr and BUN in the FA modeling group were significantly higher than those in the control group (P<0.05). In the FA modeling group, the volume and weight of both kidneys were increased, and kidney color got whiter. Under a light microscope, obvious renal tubular injury was observed, without glomerular injury. (2) Compared with the 0 h group, there was no significant difference in Scr and BUN with the 1 h, 2 h and 4 h groups (P> 0.05); Scr and BUN with the 8 h, 12 h, 24 h and 48 h groups increased significantly (P<0.05). In addition,The Scr and BUN values with the above groups gradually increased with time going, with the highest value with the 48 h group. (3) Compared with the o h group, plasma FGF23 with all the 7 experimental groups was significantly increased (P<0.05); and plasma FGF23 with all 7 experimental groups gradually increased with time going, with the highest value with the 24 h group. The value with the 48 h group decreased little compared with that with the 24 h group(P> 0.05). (4) Compared with the 0 h group, the urinary KIM-1 value with the 1 h group had no significant difference(P>0.05); the values with the 2 h, 4 h, 8 h,12 h, 24 h and 48 h groups increased significantly(P<0.05), and the values with the above groups increased gradually with time going, with the highest value with the 48 h group. (5) Slight renal tubular injury were observed in the rats 1 h after injecting FA, and the tubular injury severity and the affected area increased with time going, without observed tubular injury under an optical microscope at each time point. Conclusions (1) Plasma FGF23 has early predictive value for AKI in rats,and can be used as an early marker for AKI. (2) Plasma FGF23 has time advantage over urine KIM-1. Combination of the two parameters with 28 h may be more effective and more reliable for early diagnosis of AKI.