Nutritional Ultrasound in the Morphofunctional Assessment of Malnutrition in Patients Undergoing Incremental Versus Conventional Hemodialysis: A Comparative Study

<i>Background and Objectives</i>: Nutritional status is essential for outcomes in hemodialysis (HD) patients. Incremental HD (iHD) may help preserve residual renal function, but its effect on nutrition and body composition is unclear. Nutritional ultrasound (NUS) offers a non-invasive way to assess muscle and fat, complementing methods like BIA. This study compared nutritional status using morphofunctional assessment in patients on iHD versus conventional HD (cHD). <i>Material and Methods</i>: This single-center observational cross-sectional study included 74 stable adult HD patients (>3 months). Patients were stratified into iHD (n = 13; 1-2 sessions/week) and cHD (n = 61; 3 sessions/week). Evaluations included clinical and biochemical parameters, BIA, handgrip strength, nutritional scores and NUS assessed mass muscle of anterior quadriceps rectus femoris (QRF), supramuscular fat (SMF), subcutaneous adipose tissue (SAT), and preperitoneal visceral fat (PPVF). <i>Results</i>: Patients on iHD exhibited a more favorable nutritional and inflammatory profile, with a lower risk of malnutrition and a reduced prevalence of protein-energy wasting (PEW) syndrome. Although BIA failed to clearly differentiate between groups, NUS identified better preservation of SMF in iHD patients (8.3 ± 2.5 vs. 6.6 ± 2 mm; <i>p</i> = 0.009), as well as higher preperitoneal visceral fat thickness (1.9 ± 4.9 vs. 0.6 ± 0.3 cm; <i>p</i> = 0.04). There was also a trend toward greater muscle thickness in the iHD group, such as the Y-axis (9.5 ± 2 vs. 8.5 ± 2.3 mm; <i>p</i> = 0.17) and cross-sectional area muscle of rectus femoris (CS-MARF in cm²) (2.9 ± 0.6 vs. 2.6 ± 0.8 mm; <i>p</i> = 0.1) of anterior QRF, although without reaching statistical significance. <i>Conclusions</i>: These results highlight the value of NUS as a sensitive method for assessing nutritional status in HD patients, particularly within individualized strategies such as iHD, where it may provide key complementary information not captured by conventional methods.