Markers of chronic kidney disease in high-risk hypertensive patients: relationship with abnormal circadian blood pressure profile and intrarenal vascular resistance

Abstract

Objective. To determine the frequency of markers of chronic kidney disease (CKD) in hypertensive patients, and to assess their relationship with the circadian blood pressure (BP) profile and intrarenal vascular resistance.Design and Methods. We studied 70 patients with medically-controlled hypertension (63,2 ± 8,3 years, m — 48,6 %, office BP was 130,5 ± 13,7 / 78,1 ± 8,5 mm Hg), 40 patients were recruited from the Russian multicentre program CHRONOGRAF. Measurement of the office BP, ambulatory BP monitoring were performed. Glomerular filtration rate (GFR) was calculated using the CKD-EPI formula, and albuminuria (AU) was determined as albumin/creatinine (A/Cr) ratio in the morning portion of urine (n = 40) or 24-hour urinary albumin excretion (UAE) (n = 22). Intrarenal vascular resistance was estimated by renal duplex Doppler ultrasound. The resistive index (RI) levels in the main renal arteries (MRA) and intrarenal arteries (IRA) were calculated.Results. Markers of CKD (GFR < 60 ml/min/1,73 m2and/or A/Cr > 30 mg/g and/or UAE > 30 mg/day) were detected in 31,4 % of patients with well-medically-controlled hypertension: average values of BP-day and BP-night were normal. The frequency of markers of CKD was 44,4 % in patients with BP-night ≥ 120/70 mm Hg (40,9 %) and 28,2 % in patients with BP-night < 120/70 mm Hg (58,1 %). A/Cr ratio was positively associated (Rs = 0,3550, р = 0,0266), GFR was negatively associated (Rs = –0,3795, р = 0,002) with systolic BP-night. RI in the segmental intrarenal arteries correlated with GFR (Rs = –0,4232, p = 0,0005). Renal RI were higher in CKD-patients vs. non-CKD-patients. During the ROC-analysis, the threshold value of RI in segmental IRA 0,725 to the detection of CKD markers (sensitivity of 71,4 %, specificity of 68,9 %, AUC = 0,699) was established. Among the diabetic patients, there were more marked disturbances of renal hemodynamic in the presence of CKD markers: RI in arcuate IRA reached 0,73 (0,68–0,75).Conclusions. The high frequency of markers of CKD (31,4 %) was identified even in patients with well-medically-controlled hypertension, it was associated with systolic BP-night. The negative correlation was found between GFR and RI. Renal hemodynamics was significantly disturbed in the presence of CKD markers, especially in patients with type 2 diabetes mellitus. The cut-off point of RI in segmental IRA indicating the CKD markers is 0,725.