Impact of hydration status on body composition as measured by dual energy X-ray absorptiometry in normal volunteers and patients on haemodialysis

Abstract

To evaluate the influence of hydration status on the estimation of body composition using dual-energy X-ray absorptiometry (DXA), six normal volunteers and seven patients on maintenance haemodialysis were investigated using two different DXA machines (Lunar DPX, Hologic QDR 1000/W). Normal volunteers were studied (Hologic QDR 1000/W) before and 1 h after ingestion of breakfast, lunch and dinner (drinking various amounts of liquids at each meal, 0.5-2.4 kg). Whereas bone mineral content and body fat mass did not change, lean body mass of the trunk increased as a consequence of the meals. Conversely in patients on haemodialysis (Lunar DPX), lean body mass decreased in all segments of the body as a consequence of removal of 0.9-4.4 kg of salt-containing fluid by haemodialysis (trunk 61%, legs 30%, arms 5.5% and rest of the body 3.5%), whereas bone mineral content and body fat mass remained unchanged. However, this finding(s) did not hold true in one particular patient with bilateral hip prostheses. Measurement of body composition in eight normal volunteers on the same day with both machines showed similar results for lean and fat mass, whereas bone mineral content was found to be 17% higher using the Lunar DPX. In summary, in centres where both machines are available, follow-up of one individual patient should always be performed using the same equipment. In addition, hydration status and food intake must be taken into account when repetitive measurements of lean body mass are performed in the same patient.

Errors in Dual Energy X-Ray Absorptiometry Estimation of Body Composition Induced by Hypohydration

“…This type of intervention related to hydration status (hypo-and hyper-hydration) has only been analysed previously in non-athletic groups using 24h fluid restriction or dialysis (Going et al, 1993;Horber, Thomi, Casez, Fonteille, & Jaeger, 1992). In the present study, baseline measures (initial body mass, initial hydration status, sum of skinfolds, impedance and body composition), and environmental conditions were all consistent and demonstrated that under these experimentally controlled conditions estimates of body composition are reliable.…”

“…Studies on the influence of daily activities, meal ingestion, and acute exercise on body composition estimates have already been performed in healthy controls (Horber, Thomi, Casez, Fonteille, & Jaeger, 1992) and more recently on athletes (Nana, Slater, Hopkins, & Burke, 2013;Nana, Slater, Hopkins, & Burke, 2011). Furthermore, previous work has not compared DXA estimates with skinfolds/impedance analysis outcomes following an acute fluid deficit.…”

Comparison of anthropometry to DXA: a new prediction equation for men

“…Variations around this assumed constant can result in error. Despite this limitation, the error in %BF associated with hydration seems to be small (Horber et al, 1992). DXA is also limited in how it determines the density of tissue directly over bone.…”

Neither Heavy nor Light Load Resistance Exercise Acutely Exacerbates Lymphedema in Breast Cancer Survivor

“…DXA (Hologic Discovery A, Waltham, MA) was used to assess tissue composition of the limbs using a 3-compartment model sensitive to changes in fluid retention. 39,40 Measurements were converted into volume using known densities of adipose tissue (0.9167 g/mL ≈ 0.92 g/cm 3 ), lean tissue (1.0615 g/mL ≈ 1.06 g/cm 3 ), and bone (3.15 g/cm 3 ), a method shown to correlate very highly (r = .996, P < .0001) with total arm volume measurement by plethysmography. 41 Absolute values of the total volume for the affected arm as well as the volume difference between the affected and non-affected arms were reported.…”