Lean body mass changes in cancer patients with weight loss

Background and Aims: Metabolic measurements (e.g. resting energy expenditur e) are adjusted to lean body mass to account for body composition differenc es. Usually lean body mass is estimated from total body water. However, thi s may be compromised in weight-losing cancer patients owing to alterations in the degree of hydration of the lean body mass. This study examined the r elationship between two independent estimates of lean body mass in healthy subjects and cancer patients with weight loss. Methods and Results: Height, weight, total body water and total body potass ium were measured in healthy subjects (n = 9) and weight losing cancer pati ents (n = 13). They were similar in terms of age and gender. However, the c ancer group had a significantly lower percentage ideal body weight (P < 0.0 01). The measured total body water values in both groups were similar to th ose predicted. In contrast, measured total body potassium values in the can cer group were significantly lower than predicted (P < 0.001). There was a correlation between the ratio of measured lean body mass (water/lean bodyma ss (potassium) and the percentage weight loss (r = 0.698, P < 0.001). Conclusions: These results suggest that total body water significantly over estimates metabolically active tissue in weight-losing cancer patients and therefore its use as the basis for metabolic requirements in this group of patients is questionable. (C) 2000 Harcourt Publishers Ltd.