Faculty Bibliography

OBJECTIVE:To review how visceral and hepatic fat are measured in clinical practice and clinical research. METHODS:We examine different methods employed to assess visceral and hepatic fat in the literature. RESULTS:Fat in the human body is located in 2 main compartments: subcutaneous and visceral, which also includes liver fat. Visceral and liver fats are associated with the metabolic complications of obesity like hypertension, diabetes, and atherosclerosis. Therefore, there is a need to detect those fats early in life before the development of cardiometabolic syndrome (CMS). Many modalities have been proposed to measure visceral and liver fat. Indirect measurements can be done through waist circumference (WC), dual-energy X-ray absorptiometry (DEXA), ultrasound, and bioelectric impedance, whereas direct methods include computed tomography (CT) and magnetic resonance imaging (MRI). An ideal measurement method should be noninvasive, reliable, suitable for all body sizes, widely available, cost and time effective, show low variability, and have no or limited radiation exposure. CONCLUSION/CONCLUSIONS:Measuring visceral and liver fat is not a straightforward procedure in clinical practice or research; several variables may affect measure accuracy and validity.

BACKGROUND:One factor associated with poor outcomes in hemodialysis patients is exposure to a foreign membrane. Older membranes are very bioincompatible and increase complement activation, cause leukocytosis by activating circulating factors, which sequesters leukocytes in the lungs, and activates platelets. Recently, newer membranes have been developed that were designed to be more biocompatible. We tested if the different "optiflux" hemodialysis membranes had different effects on platelet levels. METHODS:Ninety-nine maintenance hemodialysis patients with no known systemic or hematologic diseases affecting their platelets had blood drawn immediately prior to, 90 minutes into, and immediately following their first hemodialysis session of the week. All patients were dialyzed using a Fresenius Medical Care Optiflux polysulfone membrane F160, F180, or F200 (polysulfone synthetic dialyzer membranes, 1.6 m(2), 1.8 m(2), and 2.0 m(2) surface area, respectively, electron beam sterilized). Platelet counts were measured from each sample by analysis using a CBC analyzer. RESULTS:The average age of the patients was 62.7 years; 36 were female and 63 were male. The mean platelet count pre, mid, and post dialysis was 193 (standard deviation ±74.86), 191 (standard deviation ±74.67), and 197 (standard deviation ±79.34) thousand/mm3, respectively, with no statistical differences. CONCLUSION/CONCLUSIONS:Newer membranes have no significant effect on platelet count. This suggests that they are, in fact, more biocompatible than their predecessors and may explain their association with increased survival.