Dual-energy X-ray absorptiometry: a review.

Dual-energy X-ray absorptiometry (DXA) has been recently used for body composition analysis in dialysis patients. It is based on the principle that X-rays passed through various body tissues have different attenuation and, therefore, can be differentiated. By using X-rays at two different energy levels, better tissue differentiation is possible compared with single energy systems. This article will review the evolution of DXA scanners and the role DXA has in assessing body composition in dialysis patients. Overall, this technique has excellent precision and holds promise for use in the serial evaluation of body composition and nutritional evaluation of dialysis patients.

Comparison of five body-composition methods in peritoneal dialysis patients.

Body-composition assessment is an important method of evaluating nutritional status in peritoneal dialysis patients. Because body-composition measurement estimates have not been fully validated in this population, we assessed five body-composition methods in 30 well-dialyzed peritoneal dialysis patients. The techniques studied included bioelectrical impedance analysis, dual-energy X-ray absorptiometry, total-body potassium counting, and anthropometry by two techniques. The dialysis patients were matched for age, race, sex, height, weight, and body mass index with 29 healthy control subjects in our laboratory database. By 5 x 2 x 2 analysis of variance, significant differences were found between results by modality (P < 0.0001) as well as by sex, with women having an increased percentage of fat (P < 0.0001). However, there was no significant intermethod difference by condition (peritoneal dialysis or control). That is, although significantly different percentage fat values were found between the body-composition techniques, this variability was independent of whether the measurement was made on control or peritoneal dialysis patients. Despite the differences between modalities, all techniques were found to correlate significantly with each other (P < 0.01 or better for men and P < 0.001 or better for women). Our experience shows that these routine techniques for measuring body composition can be readily applied to stable peritoneal dialysis patients.