Abstract
Background
Patients with low Body Mass Index (BMI) on maintenance hemodialysis have a higher mortality risk than patients with elevated BMI. We investigated the use of kinetic modeling to test different hypotheses which have been advanced to explain this relationship.
Methods
Equations from a three-pool urea-kinetic mathematical model (hepatic mass, extracellular fluid, muscle mass and adipose tissue) were solved to yield predictive profiles of solute and putative toxin concentrations versus time for patients of different body weights.
Results
For the interdialytic interval, our mathematic model suggests that extracellular solute/toxin concentration increases more rapidly in small patients. Additionally, time average concentration (TAC) is higher for this cohort. A lower value of the muscle mass and adipose tissue mass-transfer coefficient (KMMAT), which determines the rate of solute release into the extracellular fluid, exacerbates this difference.
Conclusion
These results suggest that higher mortality for smaller dialysis patients may be mediated by higher time average toxin concentration, especially for solutes with a low mass-transfer coefficient value.
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