Features of Kidney Function in Patients With Comorbidity of Arterial Hypertension and Chronic Obstructive Pulmonary Disease

Background and objective Chronic kidney disease (CKD) and hypertension are closely linked in terms of cause and effect. Decreased renal function is usually associated with increased blood pressure, and a steady increase in blood pressure accelerates the decline in renal function. In this study, we aimed to investigate laboratory parameters of renal function - blood creatinine level, urine creatinine level, urea blood level, urine albumin level, and in particular, serum cystatin C level - as early predictors of kidney damage and assess the filtration function of the kidneys based on the glomerular filtration rate (GFR) in patients with isolated arterial hypertension, those with a comorbid pathology of hypertension and chronic obstructive pulmonary disease (COPD). and those with isolated COPD. Materials and methods The study included a total of 101 patients (the final sample consisted of 88 patients) with hypertension and COPD, who were divided into three groups: Group I consisted of 38 patients with hypertension, Group II comprised 27 patients with hypertension and COPD, and Group III was made up of 23 patients with COPD. The average age of patients in groups - presented as mean [standard deviation (SD)] - was as follows - Group I: 55.7 (11.2) years, Group II: 59.3 (9.2) years, and Group III: 57.8 (9.1) years. For statistical data processing, the program Statistics 10 was used. Results The level of blood creatinine - presented as median (Me) and interquartile range (IQR) - was statistically significantly different between the groups, and the values in the three groups were as follows - Group I (patients with hypertension): 88.3 (84.2; 102.7) μmol/l, Group II (patients with comorbid pathology of arterial hypertension and COPD): 99.0 (80.0; 115.0) μmol/l, and Group III (patients with COPD): 84.6 (75.0; 94.2) μmol/l (p=0.008). The highest level was determined in patients with hypertension and comorbid COPD, while the lowest was in the comparison group, in patients with COPD. Urinary creatinine levels were as follows - Group I: 1081.0 (578.0; 1749.0) mg/l, Group II: 1318.5 (1124.0; 1817.0) mg/l, and Group III: 822.0 (625.0; 1320.5) mg/l (p=0.08). Blood urea values were as follows - Group I: 5.7 (5.2; 6.0) mmol/l, Group II: 5.7 (4.9; 6.6) mmol/l, Group III: 5.9 (4.4; 7.7) mmol/l. The calculation of GFR revealed a statistically significant difference between the three groups - Group I: 70.5 (56.0; 83.0) ml/min, Group II: 66.5 (57.0; 77.0) ml/min, and Group III: 81.5 (70.0; 88.0) ml/min (p=0.02). The cystatin C level was 1.16 (1.03; 1.27) mg/l in Group I, 1.3 (1.22; 1.38) mg/l in Group II, and 1.05 (0.96; 1.05) mg/l in Group III. Conclusions In patients of all three groups, there was a decrease in renal filtration function based on the results of creatinine and cystatin C levels. Even in the group of patients with COPD without kidney disease, a decrease in GFR was observed. We noted a negative aggravating effect of COPD on renal function in patients with hypertension, which can be attributed to increased endothelial dysfunction and increased general inflammation in this group of patients.