Background: The diagnosis of chronic kidney disease (CKD) is usually delayed, when significant functional renal impairment has already occurred. The diagnosis is complex and clinical and laboratory investigations play a crucial role. There are well-established markers of CKD – serum creatinine and cystatin C. However, the search for new reliable biomarkers that aid in the assessment of kidney function and predict the evolution of the disease is still in progress. Objective: To investigate the role of serum uromodulin (sUmod) as a marker for early diagnosis of renal impairment in patients with CKD. Materials and Methods: We investigated 70 patients, 28 male and 42 female, mean age 56.53 ± 11.753, with CKD in a prospective observational study. All patients were admitted to the Clinic of Nephrology at the “St. Ivan Rilski” University Hospital between April and November 2019. After obtaining written informed consent, laboratory blood and urine tests, abdominal ultrasound and sUmod investigations were performed in all patients. Results: Plasma uromodulin levels showed decrease with the increasing of the severity of renal impairment. sUmod displayed inverse correlation with serum creatinine (r = -0.467, p < 0.0001), cystatin C (r = -0.430, p < 0.0001) and urea (r = -0.495, p < 0.0001) and a positive correlation with eGFR (r = 0.628, p < 0.0001). Conclusion: The results of our study show that sUmod levels significantly correlate with all established laboratory parameters used for the evaluation of renal impairment. It can be used as a potential early biomarker for CKD diagnosis.

Background: One of the most common causes of renal impairment and development of chronic kidney disease is diabetes mellitus type 2 (DM 2). The aim of this prospective study was to determine the role of Resistive Index (RI) as a non-invasive marker for the evaluation of renal impairment in patients with DM 2. Material and Methods: 47 patients with DM 2 in mean age 62.66 ± 10.081 years were included in the study for the period of one year. All of them were with well-compensated diabetes mellitus (HbA1c < 7.0%) and optimal control of arterial hypertension. Hematological analysis of blood were carried out. Serum and urine biochemical parameters were tested, glomerular filtration rate (GFR) was calculated, and abdominal ultrasound with measure of RI was done. Results: Patients with RI < 0.7 and those with RI ≥ 0.7 did not differ significantly in terms of their age, sex, body mass index (BMI), duration of DM 2 and arterial hypertension, use of antihypertensive drugs and HbA1c (p > 0.05 for all). There was significant difference between the groups according to serum creatinine (p = 0.026), GFR (p = 0.044) and the degree of proteinuria (p = 0.001). There was a positive correlation between RI and serum creatinine (r = 0.418; p = 0.001) and between RI and proteinuria (r = 0.396; p = 0.004). A negative correlation relationship between RI and GFR values was found (r = −0.413; p = 0.011). Conclusions: RI may be used as an indicator for the assessment of the severity of renal impairment in patients with DM 2. It correlates well with serum creatinine, GFR and proteinuria, which are proven biochemical parameters indicating the degree of renal damage in patients with DM 2.