Introduction. The outcome of surgical treatment of renal cancer depends not only on cancer-specific survival, but also on the degree of loss of renal function, which often develops after surgery, especially radical nephrectomy.
Aim. To study the features of functional changes in a solitary kidney as a compensation mechanism after radical nephrectomy for renal cancer.
Materials and methods. The functional state of a solitary kidney in 36 patients with renal cancer who undergone to radical nephrectomy was evaluated. There were 20 and 16 women. The mean age was 59.0±10.8 years (from 39 to 76 years). The size of the tumor was in the range of 7.0–12.0 cm. All patients with a solitary kidney underwent a follow-up examination 3 months after surgery, including measurement of peripheral blood pressure with calculation of mean dynamic pressure, renal ultrasound, calculation of glomerular filtration rate (GFR), renal doppler ultrasound, determination of serum fibrinogen and fibrin monomers, and microscopy of the bulbar conjunctiva. Patients who had pathological abnormalities during the examination were prescribed reno-cardioprotective drugs, including perindopril in a titrated dose, apixaban 5 mg a day as thromboprophylaxis and for improvement of the flow properties of blood for a period of 3 months with re-evaluation of the above parameters.
Results. In 61.1% of patients after radical nephrectomy, on 2–4 postoperative days, there was a tendency to increase blood pressure compared to baseline values (p<0.05). By the seventh day after the procedure, the volume of the contralateral kidney increased on average by 16% (from 110.4±11.2 cm3 to 132.4±4.8 cm3, p<0.05). After radical nephrectomy, a decrease in GFR was detected in 33 cases (91.7%; p<0.05). Renal doppler ultrasound showed a moderate increase in linear blood flow, the resistance index in the main renal artery, and a decrease in the pulse index in the segmental and arcuate arteries. The microscopy of the bulbar conjunctiva in 83.3% of patients revealed changes in the microcirculatory bed, including narrowing of arterioles, dilation of venules, a decrease in venular and capillary blood flow. After 3 months of reno-cardioprotective therapy, it was revealed that the target values of blood pressure (<130/85 mm Hg) were achieved with an average dynamic blood pressure of 93.4±2.6 mm Hg. In addition, a decrease in creatinine to an average of 106.2±6.4, fibrinogen and fibrin monomers to subnormal values of 3.2±0.2 g/l and up to 8.1±0.5x10-2 g/l, respectively were seen. Renal hypertrophy according to ultrasound examination was preserved with a mean kidney volume 119.7±3.6 cm3. Disturbances in peripheral microcirculation according to the microscopy of the bulbar conjunctiva was assessed as moderate.
Conclusion. The development of CKD in patients with a solitary kidney is accompanied by a structural reorganization of the organ with an increase in blood pressure, an increase in its volume, a decrease in function, microcirculatory disorders and hypertensive nephropathy. Considering the prognostic significance of changes in the solitary kidney, it is important not only to control the functional parameters, but also to include reno- cardioprotective therapy as a standard, since it contributes to the preservation of the renal function and prevents the rapid progression of CKD. Thus, medical and social rehabilitation of patients with a solitary kidney is required. However, it is currently cannot be considered comprehensive.

Keywords: kidney cancer, solitary kidney, chronic kidney disease