Assessment of Body Composition Using Dry Mass Index and Ratio of Total Body Water to Estimated Volume Based on Bioelectrical Impedance Analysis in Chronic Kidney Disease Patients

摘要

Objective: Body mass index (BMI) is commonly used for assessment of nutritional status. However, changes in BMI in chronic kidney disease (CKD) patients are affected not only by muscle and fat but also by fluid volume. The ratio of extracellular water (ECWBIA) to total body water (TBWBIA) in multifrequency bioelectrical impedance analysis is commonly used for assessing abnormal fluid status. This study reexamines ECWBIA/TBWBIA and evaluates the reliability of TBWBIA/TBWwatson and dry mass index (DMI) in the assessment of fluid and nutritional status. Design, Setting, and Subjects: TBWBIA, intracellular water (ICWBIA), and ECWBIA were measured in 45 randomly selected CKD patients. Participants were surveyed for age, gender, BMI, blood pressure, serum albumin, estimated glomerular filtration rate, and proteinuria. DMI was calculated by the formula ([weight - TBWBIA]/height2) and TBWBIA/TBWwatson using an anthropometric formula (Watson). Fluid and nutritional status were assessed using ECWBIA/TBWBIA, TBWBIA/TBWwatson, and DMI. Results: TBWBIA/TBWwatson positively correlated with weight, BMI, and diastolic blood pressure and negatively correlated with age and serum albumin level. In contrast, ECWBIA/TBWBIA correlated with ICW deficit, aging, and body weight loss. On the basis of DMI and TBWBIA/TBWwatson, participants were categorized as follows: 1 obese patient with hypovolemia and 2 with euvolemia; 17 overweight patients with hypovolemia (n = 6), euvolemia (n = 8), or hypervolemia (n = 3); 24 patients of optimal weight with hypovolemia (n = 10), euvolemia (n = 9), or hypervolemia (n = 5); and 1 underweight patient with euvolemia. Conclusions: A combination of DMI, BMI, and TBWBIA/TBWwatson makes it possible to include assessment of fluid volume to the physique index. In addition, ECWBIA/TBWBIA is not a reliable marker of edematous state in CKD patients. ? 2013 National Kidney Foundation, Inc.