Renal dysfunction in patients with resistant hypertension: association with clinical profile and fat depots

Introduction. Chronic kidney disease (CKD) and arterial hypertension (AH), especially its resistant forms, are two closely related and mutually aggravating diseases. The pathophysiology of CKD development in patients with resistant AH is complex and is not limited to the negative impact of hemodynamic, metabolic, neurohormonal and proinflammatory factors. The common pathophysiological mechanism of development of both diseases is visceral obesity, which has both systemic and local negative effects. However, aspects of kidney damage in patients with resistant AH (RAH) require further study, and their understanding may open up new possibilities in a comprehensive approach to nephroprotection. Aim: To study the relationship between a decrease in the functional state of the kidneys in patients with resistant hypertension and clinical data, the size of systemic and local fat depots, as well as markers of sympathetic activity. Material and Methods. Sixty-three patients with RAH were included in comparative cross-sectional study. CKD C3 was documented in 19 patients (30%). Magnetic resonance imaging (MRI) (1.5 Tesla) was used to assess the sizes of kidney and abdominal fat depots (thickness and area of subcutaneous and visceral adipose tissue (S SAT and VAT), paranephral adipose tissue thickness (PRAT). In addition to routine examinations, patients underwent measurement of cystatin C levels in the blood and 24-hour blood pressure monitoring. Activity of sympathetic nervous system was assessed by catecholamine’s measuring in urine and blood tests, beta-adrenergic membrane reactivity (β-ARM) of erythrocytes, and systolic BP variability. Results. Patients with CKD compared to patients without CKD were older, higher pulse BP levels ( p = 0.005), fasting glucose ( p = 0,007), had smaller kidney sizes ( p = 0.046), S VAT ( p = 0.025) and PRAT thickness ( p = 0.013), and lower kidney diameter/PRAT ratio ( p = 0.022). No intergroup differences were found in anthropometric indices, SAT thickness and markers of sympathetic activity. Decreased estimated glomerular filtration rate (eGFR) had quantitative associations with increased PRAT thickness and percent adipose tissue (AT) ( r = –0.27, p < 0.05 for both)). High uric acid levels correlated with increased S VAT, PRAT thickness and a set of anthropometric parameters. Conclusions. The presence of CKD in patients with RAH is associated not only with age, an increase in pulse BP and fasting glucose, but also with an increase in the size of visceral fat depots, and a decrease in the functional state of the kidneys is directly related to an increase in adipose tissue in the perirenal region, the percentage of adipose tissue and an increase in vascular stiffness.