Kidney damage in hypertension disease

Essential hypertension (EH) is the most common cardiovascular disease and the leading cause of chronic kidney disease  (CKD) worldwide. The aim of the study was to investigate the frequency and nature of kidney damage in hypertension. 189  patients (69 men and 120 women) with hypertension (stages I, II, and III) aged 43 years and older were examined. The average age of the patients was 61.2 ± 8.7 years. Clinical and biochemical tests were conducted on all patients, including red blood  cell indices, C-reactive protein (CRP), lipid profile, fibrinogen, electrolytes, glucose, uric acid, creatinine, and cystatin C. The  duration of hypertension was also recorded for each patient. Kidney function was assessed using serum creatinine (CKD-EPI)  and cystatin C (F. Houcke). Patients were categorized according to the degree of decrease in glomerular filtration rate (GFR)  based on the recommendations of the Russian Nephrology Society. Patients with kidney damage were divided into two groups:  Group 1 consisted of patients with hypertension without signs of CKD (GFR calculated by cystatin C ≥ 60 ml/min), while  Group 2 consisted of patients with hypertension complicated by CKD. The results showed that hypertension was accompanied  by target organ damage in 70.8% of cases. The prevalence of CKD among patients with hypertension was 28.5%. Proteinuria  was mainly detected in patients with renal insufficiency. The frequency of GFR categories according to CKD-EPI and F.  Houcke formulas was as follows: G1 — 54.4% and 13.7% (p < 0.05); G2 — 35.9% and 57.6% (p < 0.05); G3a — 5.2% and  19.5% (p < 0.05); G3b — 3.1% and 5.2% (p < 0.05); G4 — 0.5% and 3.1% (p < 0.05) and G5 — 0.5% and 0.5%, respectively.  There was a strong correlation between GFR and serum creatinine (r = –0.439; p < 0.05) and cystatin C (r = –0.866;  p < 0.0001). Patients in Group 2 (hypertension with kidney damage) had significantly higher levels of CRP, low-density  lipoprotein cholesterol, cystatin C, and longer duration of hypertension, but lower levels of total calcium than patients in  Group 1. In conclusion, CKD was present in 28.5% of patients with hypertension, and proteinuria was mainly detected in  patients with renal insufficiency. Serum cystatin C levels most accurately reflect kidney filtration function.