title: Size matters: body composition and outcomes in maintenance hemodialysis patients.
abstract: In hemodialysis patients a low body mass index (BMI) is correlated with an unfavorable clinical outcome, a phenomenon known as "reverse epidemiology". Mechanisms underlying this observation are unclear. We propose the following: uremic toxin generation occurs predominantly in visceral organs and the mass of key uremiogenic viscera (gut, liver) relative to body weight is higher in small people. Consequently, the rate of uremic toxin generation per unit of BMI is higher in patients with a low BMI. Body water, mainly determined by muscle mass, serves as a dilution compartment for uremic toxins. Therefore, the concentration of uremic toxins is higher in small subjects. Uremic toxins are taken up by adipose and muscle tissues, subsequently metabolized and stored. Thus, the larger the ratio of fat and muscle mass to visceral mass, the lower the concentration of uremic toxins and the better the survival. To test this hypothesis, studies on uremic toxin kinetics in relation to body composition are needed.
authors.affiliation: Department of Internal Medicine, Krankenhaus der Barmherzigen Bruder, Marschallgasse 12, AT-8020 Graz, Austria. Kotanko1@eunet.at
authors.forename: Peter
authors.initials: P
authors.lastname: Kotanko
authors.forename: Stephan
authors.initials: S
authors.lastname: Thijssen
authors.forename: Thomas
authors.initials: T
authors.lastname: Kitzler
authors.forename: Grzegorz
authors.initials: G
authors.lastname: Wystrychowski
authors.forename: Shubho R
authors.initials: SR
authors.lastname: Sarkar
authors.forename: Fansan
authors.initials: F
authors.lastname: Zhu
authors.forename: Frank
authors.initials: F
authors.lastname: Gotch
authors.forename: Nathan W
authors.initials: NW
authors.lastname: Levin
mesh_terms: D001481:Basal Metabolism / Q000502:physiology*; D001823:Body Composition; D015992:Body Mass Index; D006801:Humans; D006435:Renal Dialysis / Q000009:adverse effects*; D016896:Treatment Outcome; D014511:Uremia / Q000503:physiopathology*