Effect of aging on the body composition of dialyzed subjects. Comparison with normal subjects.

A bioimpedance analyzer (BIA-CHIP; Akern RJL System) was applied to 366 normal subjects (171 men and 195 women). Each gender group was divided into eight groups, according to age: 20-29 years; 30-39 years; 40-49 years; 50-59 years; 60-69 years; 70-79 years; 80-89 years; and 90-95 years. The same was done with 44 hemodialysis patients (22 men, 22 women), each being evaluated 15 times over a period of 5 years: these were divided into seven groups (seven, because no patient was older than 89) using the same criteria. For each subject, 23 parameters were determined: 5 directly measured (height, weight, resistance, reactance, phase angle) and the others (fat and lean mass, body water, body cell mass, extra and intracellular water, etc.) from appropriate equations. Twenty-four thousand data points were collected and served to form a data bank. Men and women on hemodialysis showed different effects of aging: women normalized their BC at an age > 70 years, whereas men continued to have a muscle mass lower than that of normal subjects until the age of 80. A computerized program (Nutritio) permits fast and reliable evaluation of the nutritional status of hemodialysis patients, each subject being compared with both the similarly aged population (dialyzed or not) or with his or her own data, obtained over time.