Phosphate Kinetic Modeling 2

PKM consists of a set of validated and computerized algorithms to perform the following steps:

1. Calculate calcium (Ca) and phosphorus (P) intake and absorption in individual patients as a function of the prescribed doses of Vitamin D analogues, protein catabolic rate (PCR) and dietary and binder Ca intakes.
2. Calculate P removal between dialyses by P binders and P and Ca removal during dialysis from kinetic analysis of total P and Ca transport during dialysis based on dialyzer P and Ca transport coefficients and the levels of dialysate Ca and serum Ca and P.
3. Thus from analysis of intake, absorption and removal the program can calculate net Ca and P balance in modeled patients.
4. Calculate the daily dose of phosphate binder (PhosLo) required to reduce the serum P to normal in patients with hyperphosphatemia.
5. Calculate the dialysate Ca required to achieve zero calcium balance over complete dialysis cycles - the interdialytic interval and immediately succeeding dialytic interval.
6. The program also computes a Phosphorus-Protein ratio (PPR, the total P removed divided by PCR, mg/gm/day) which provides a quantitative index of compliance with prescribed dietary P restriction and/or the prescribed dose of binders. It is hoped that this information will be valuable to guide semi-quantitative evaluations of diet P and binder intakes in patients difficult to manage. Study subjects will bring their PhosLo pill bottles to treatments weekly. At this time the subject's dietitian will determine and record the remaining pills. The comparison of pills taken versus pilled prescribed will be performed with any data available. While weekly counts are desirable for providing more information about the consistency of a patient's compliance, a minimum of monthly counts will be sufficient. This will be done to validate the PPR range needed to accurately identify compliance with PhosLo regimen. Patients will also be instructed to bring all empty PhosLo bottles to site dietitian. The site dietitian will record pill count data in a form for each patient. The updated version of the PKM algorithm also includes computation of the dose of vitamin D analogues and cinacalcet (Sensipar). This modification of the PKM algorithm may help to better achieve neutral calcium balance, because the intestinal calcium absorption heavily depends on vitamin D levels. The computation of cinacalcet aids the control of parathyroid hormone (PTH) levels within the target range.