Research briefBody composition of patients on a very low-protein diet: a two-year survey with DEXA
Section snippets
Patients and methods
Thirteen ambulatory patients (8 men, 5 women; age range, 39–70 years; average age, 55 ± 12 years) with advanced chronic renal failure (CRF) (mean glomerular filtration rate [GFR] measured using urinary clearance of 51Cr EDTA, 15 ± 4.7 mL/min/1.73 m2) were enrolled in the study. SVLPD was proposed to all adult patients with advanced CRF, excluding those with severe comorbid conditions that might superimpose a hypercatabolic state. Patients who obviously could not adapt to the dietary
Body composition
To determine body composition, a whole-body scan was performed using a fan-beam model QDR-4500A dual-energy x-ray absorptiometry (DEXA) densitometer (Hologic Inc, Waltham, MA).
The scan time was 3 minutes, and the radiation dose was approximately 2 μSv per scan. Total and regional analyses were performed using the standard manufacturer’s protocol. A segmentation of the whole-body image was obtained in 6 subregions: left arm, right arm, trunk, left leg, right leg, and head. In each, the results
Statistics
Data are expressed as mean ± 1 SD. ANOVA for repeated measures (alpha level, 5%) was first used to compare body composition data at different times, then a paired t-test was used to compare 2 time points for LBM and biologic values at T0, T12, and T24 months. Analyses were performed using Stat View 5.0 (Abacus Concept, Berkeley, CA).
Results
The average baseline and 24-month clinical and blood chemistry values are reported in Table 1. Blood urea values significantly decreased from T0 to T24 in accordance with low protein intake. The compliance was good and assessed by the urea urinary excretion as shown in Figure 1. Protein intake was 0.81 ± 0.29 before VLPD, 0.31 ± 0.08 at 3 months, 0.39 ± 0.15 at 12 months, and 0.38 ± 0.12 g/kg/day at 24 months. No significant variation existed from month 3 to month 24 at quarterly evaluation.
DEXA results
Body mass index remained stable during the 24-month follow-up. No significant change occurred in total fat mass or percentage of fat mass between T0 and T24.
After an initial decrease in LBM in the first 3 months, from 44.9 ± 11.8 Kg to 43.7 ± 11 (mean difference, 1.387 kg; paired t test P = .034), a progressive increase occurred resulting in a significant increase of 2 kg (P = .027), whereas there was no significant change per the overall follow-up (P = .2). These evolutions in LBM are shown in
Discussion
In this 2-year prospective study, we have followed up for 2 years the course of nutritional status and body composition of 13 patients with advanced CRF put on a SVLPD. Body weight and body composition evolved into 2 distinct phases after the initiation of the dietary prescription.
During the first 3 months, LBM decreased, particularly in men, whereas fat mass did not change. After the third month, even with a slight but not significant progression of renal failure, body weight increased
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