The Rationale and Ultimate Limitations of Urea Kinetic Modelling in the Estimation of Nutritional Status

Objective This paper reviews protein flux and amino acid metabolism and the potential inaccuracies inherent in using urea kinetics as an estimate of these processes, particularly in the patient undergoing peritoneal dialysis. The problems of extrapolating these estimates back to the whole patient are examined, addressing assumptions about neutral nitrogen balance, and the difficult issue of normalizing urea-derived indices to body size. Conclusions Urea kinetics can be a helpful tool for assessing nutritional indices, but there are many caveats and many pitfalls that must be kept in mind to avoid being lulled into a false sense of confidence by the comfort of numbers.