Body composition changes in patients with human immunodeficiency virus infection

Malnutrition characterized by weight loss and often extreme wasting generally develops when patients progress from infection with human immunodeficiency virus (HIV) to AIDS. There is evidence that before the development of AIDS, HIV-infected patients without weight loss show early signs of malnutrition, defined as an increase in the ratio of extracellular mass (ECM) to body cell mass (BCM). As part of a dietary intervention study, body composition measurement were obtained at baseline and after 6 wk in 18 patients with HIV infection and CD4 counts between 140 and 740 cells/mm3. Only one patient had a prior weight loss (3.7 kg); patients gained 2 pounds after 3 wk of dietary supplementation of 500 kcal daily. Bioelectrical impedance was used to measured body compartments. The average ECM/BCM ratio (0.77 +/- 0.13) was within the normal range (0.83 +/- 0.16) indicating the absence of malnutrition by this criterion. Most measurements of BCM (kg) approximated normal values, while several for BCM (kg) exceeded normal. BCM (kg) correlated poorly with the ECM/BCM ratio (r2 = 0.08; P = 0.11) in contrast to ECM (kg), which was well correlated (r2 = 0.82; P = 0.00). In addition, there was a significant correlation of body mass index (BMI) with the ECM/BCM ratio (r2 = 0.38; P = 0.00) and with ECM (r2 = 0.244; P = 0.003) indicating that overweight patients may be more likely to be considered malnourished than normal weight patients using this ratio. Without use of bioelectrical impedance, these subtle changes might be missed. Once significant weight loss has occurred coupled with decreases in BCM (kg), the ECM/BCM ratio may be more reflective of malnutrition. These conjectures will require prospective evaluation, but for now it seems reasonable to include bioelectrical impedance as a potentially useful tool in the evaluation of malnutrition in this population.