[Investigation of serum cysteine concentration to monitor glomerular filtration rate for early diagnosis of acute kidney injury in patients with combined trauma].

AIM: / To determine the early diagnostic criteria for acute kidney injury in patients with combined trauma using serum cystatin C as a biomarker in the diagnostic work-up of the affected patients.

MATERIALS AND METHODS: / The study comprised 42 patients who suffered combined trauma from 2015 to 2016. Cystatin C level was measured in serum. Blood sampling was done on the 1st, 3rd, 7th, 14th day of the injury. The patients were predominantly men (80%). Renal function was tested by measuring the rate of filtration and reabsorption using the Reberg-Tareev test. All patients were tested for the following parameters: serum and urine creatinine, 1-minute, 1-hour and 24-hour urine output, the rate of glomerular filtration and tubular reabsorption.

RESULTS AND DISCUSSION: / Forty (95.3%) patients had normal Reberg-Tareev test values. In 2 (4.7%) patients Reberg-Tareev test results were below normal values, which was associated with the development of acute renal failure on the sixth or seventh day after trauma. The overwhelming majority of patients with combined trauma had a normal serum creatinine level (n=38). In 33 (78.6%) patients serum cystatin C level was more than 30 percent above normal values. Moreover, an increase in the cystatin C level was observed in the first 3 days, with a gradual decrease thereafter. The glomerular filtration rate, according to the Reberg-Tareev test was reduced only in 4 patients, but when the Hawk formula was used to calculate GFR, it was reduced in 33 patients. On the 3rd day after trauma, based on the increase in the serum cystatin level, 12 patients were found to have subclinical acute renal damage. At the same time, this group of patients had normal azotemia parameters. These findings suggest that measuring glomerular filtration rate using serum cystatin C has a greater accuracy in detecting latent renal dysfunction.