PATHOGENETIC ASPECTS OF THE DEVELOPMENT OF UROLITHIASIS IN KIDNEY TRANSPLANT RECIPIENTS

The aim of this study is to investigate the incidence of urolithiasis in kidney transplant recipients and evaluate the potential of using minimally invasive treatment techniques for these patients. Patients underwent ultrasound examination of the transplanted kidney and urinary tract during regular screening. When a concretion was found, multispiral computed tomography was additionally performed to clarify the size, location, and X-ray density of the concretion. We did not perform contrast enhancement to avoid acute kidney damage to the graft. Additionally, all patients underwent a comprehensive examination with the evaluation of clinical tests of blood, urine, biochemical blood analysis (including creatinine, urea, phosphorus, magnesium, calcium, parathyroid hormone). The patients with a stone of up to 5 mm in diameter and X-ray density below 1000 HU were prescribed dynamic follow-up and litholytic therapy. Contact ureterolithotripsy was performed in the patients with stones of more than 6 mm in diameter. We studied the mineral composition of stones after lithotripsy using infrared spectroscopy. According to the results obtained, the detection rate of urolithiasis in kidney transplant recipients was 7.8%. The patients with graft and urinary tract stones showed a significant increase in the level of parathyroid hormone and blood calcium, leukocyturia of varying severity compared to the patients without urolithiasis. After performing contact ureterolithotripsy, the "stone free" state was achieved in all patients and confirmed by a control ultrasound examination on the fifth day after lithotripsy. Infrared spectroscopy of the removed stone fragments demonstrated their mixed mineral composition, the dominant component of which was calcium phosphate. The data obtained point out the possible pathogenetic factors of the formation of urinary stones in kidney transplant recipients are hyperparathyroidism and the resulting hypocalcaemia, as well as urinary tract infection. Contact lithotripsy should be considered as the method of first choice in this group of patients.