After obtaining ethical board approval (Number: 419011325-050.99), patients were prospectively included for this study beginning from December 2019 - May 2020. Patients >5 years of age and had kidney stones (>3 mm) that were confirmed by two consecutive ultrasonographic images or a computed tomography and those had normal serum chemistries were included in the study. Those with congenital heart diseases, chronic kidney disease, inflammatory bowel disease, monogenic stone phenotypes, normal serum chemistries, urogenital malformations (vesicoureteral reflux, posterior urethral valves, neuropathic bladder etc.), obesity, hypertension, chronic diseases (i.e., diabetes mellitus) and patients who were passive smokers were excluded.
Blood pressures were measured from the left arm using age-appropriate manual sphygmomanometer cuffs after 5 minutes of resting and mean of 3 measurements were noted. All blood samples including urea, creatinine, glucose, uric acid, total cholesterol, triglyceride, high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C) were obtained a.m. after 8 hours of fasting. Glomerular Filtration Rate (GFR) was calculated by Schwartz formula .
Control group consisted of health children who have normal BMI and blood pressure (adjusted for age) with no known history of urolithiasis (confirmed by urinary ultrasonography).
M-mode echocardiographic measurements
Echocardiographic investigations were performed using Philips Affiniti 50 (Philips Healthcare, Andover, Netherlands) with 2.0-4.0 MHz transducers. Echocardiograms were recorded on a half-inch VHS videotape. All measurements were performed according to the American Society of Echocardiography by the same observer blinded to the participant’s clinical details . The measurements were obtained during 3 consecutive cardiac cycles and the average values were computed. Ejection fraction and fractional shortening of the left ventricle (LV), interventricular septum systolic (IVSs) and diastolic thickness, LV end-systolic and end-diastolic dimensions, and LV posterior wall systolic and diastolic thicknesses were measured from M-mode echocardiographic tracings obtained at midchordal leveling the parasternal long axis view. The left ventricular mass (LVM) was estimated by using the anatomically validated formula of Devereux and Reichek . The LVM index (LVMI) was calculated by dividing the LVM with the height (2.7).
Pulsed Doppler echocardiographic measurements
Ventricular functions were evaluated using the following pulse-wave Doppler (PWD) echocardiographic parameters: early (E) and late (A) mitral/tricuspid diastolic velocities, E/A ratio, and LV/right ventricle (RV) ejection times. Standard measurement techniques were used for evaluation . We calculated the myocardial performance index (MPI) using the formula, the sum of isovolumic contraction and relaxation times divided by the ejection time .
Tissue Doppler echocardiographic measurements
Tissue Doppler velocities; peak early diastolic myocardial (e’), peak atrial systolic (a’), and peak systolic (s’) myocardial velocities were measured by standard technique . Also, e’/a’ and E/e’ ratios were calculated. The Tei index (MPI) was calculated as defined above.
Measurement of epicardial fat tissue thickness
The EFT thickness was identified as an echo-free space in the pericardial layers on 2-dimensional echocardiography, and its thickness was measured perpendicularly on the free wall of the RV at end diastole from the parasternal long-axis views . The mean EFT thickness was calculated from 3 consecutive measurements.
Measurement of common carotid artery intima-media thickness
Longitudinal images of the common carotid artery were obtained by combined 2-dimensional mode and color Doppler examinations. On a longitudinal echocardiographic image of the posterior wall of the carotid artery was displayed as 2 bright white lines separated by a hypoechogenic space . The mean cIMT was calculated from the 3 consecutive measurements of the maximum far wall thickness obtained from 10 mm below the carotid bulb.
Measurements of periaortic fat thickness
Measurement of PFT thickness was done with conventional methods from the adventitia layer of the abdominal aorta and the adventitial layer of the aorta adjacent to the form of the measurement of the linear echogenic line. Periaortic fat tissue cannot be directly distinguished with echocardiographic and ultrasonographic images in deep tissue. Therefore, it should be measured with adventitia. Measurements were taken in the axial plane in the supine position at the L1–2 level (just above the umbilicus), proximal to the iliac bifurcation. Evaluation was repeated three times and the mean value was calculated.
The compatibility of numerical variables to normal distribution was examined using the Shapiro-Wilk test. Descriptive findings were presented as number, percentage mean and standard deviation. Comparisons between groups were made by Chi-Square test for categorical variables, and t test for independent groups if assumptions were met for numerical variables, otherwise by Mann-Whitney U test. Statistical significance level was accepted as p <0.05.