Associations of proteinuria, fluid volume imbalance, and body mass index with circadian ambulatory blood pressure in chronic kidney disease patients.

BACKGROUND/AIMS Obesity and hypervolemic status are the main causes of hypertension in patients with chronic kidney disease (CKD). However, it is difficult to differentiate between them. We aimed to assess the associations of body mass index (BMI) and total body water (TBW) with ambulatory blood pressure (ABP). METHODS Body composition by bioelectrical impedance analysis (BIA) and 24-h ABP were measured in 40 patients with CKD. TBW was assessed using corrected TBWBIA adjusted for body surface area (cTBWBIA) and the TBWBIA/TBWWatson ratio obtained using an anthropometric formula (Watson). RESULTS Elevated ABP (average 24-h BP ≥ 135/85 mmHg) was noted in 23 patients, who were more likely to have a higher cTBWBIA and TBWBIA/TBWWatson ratio than patients without elevated BP. Patients with nocturnal non-dipping (<10% drop in BP during sleep) were more likely to have a higher TBWBIA/TBWWatson ratio. Proteinuria and the TBWBIA/TBWWatson ratio were significant independent factors for 24-h ABP. BMI had a positive correlation with the cTBWBIA, TBWBIA/TBWWatson ratio and furosemide use. CONCLUSION Hypertension is dependent on proteinuria and fluid volume imbalance. The TBWBIA/TBWWatson ratio can serve as an indicator of fluid volume-dependent hypertension. BMI is affected by TBW, in which case BMI can become less involved with 24-h ABP.