Relationship between blood pressure and body composition in chronic kidney disease patients: dry mass index and ratio of total body water to estimate total body water

Obesity and hypervolemic status are mainly one of causes of hypertension in chronic kidney disease (CKD) patients. However, it is difficult to assess these factors because changes in body weight (BW) in CKD patients are affected not only by muscle and fat, but also by fluid status. The objective of this study is to assess the relationship between blood pressure (BP) and body composition using dry mass index (DMI), which subtracts total body water (TBWBIA) from BW, and a ratio of TBWBIA to estimated TBWwatson by anthropometric formula (Watson). In 40 randomly selected CKD patients, body composition and BP measured by bioelectrical impedance analysis (BIA) and by 24 hour ambulatory BP monitoring, respectively. Based on DMI and TBWBIA/TBWwatson ratio, participants were categorized into 3 of obese, 15 of overweight, 21 of optimal weight, and one of underweight, or into 13 with hypovolemia, 19 with euvolemia, and 8 hypervolemia.Empty CellDMITBWBIA/TBWwatsonrprpDaytime sBP-0.0050.9980.4290.006Night-time sBP-0.0860.5880.534<0.001Non-dipping status0.0950.5580.413<0.001 Ambulatory BP was associated with the ratio of TBWBIA to TBWwatson. In conclusion, the ratio of TBWBIA to TBWwatson is a reliable marker of fluid status, which is of practical use to assess cause of hypertension in CKD patients.