Background and objectiveChronic 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.