Acute Changes in the Mineral Metabolism After a High Phosphorous Containing Meal in Dialysis Patients

The purpose of the study is to investigate whether a high phosphorous containing meal causes acute changes in p-phosphate levels in patients with dialysis-dependent kidney failure.

Disturbances in the mineral metabolism and especially the phosphate metabolism is associated with increased risk of cardiovascular disease and death in patients with kidney failure. In the healthy population the kidney compensates for a high phosphorous intake by increase renal excretion of phosphate, but this is not possible for patients with kidney failure. Due to this monitoring and controlling phosphate levels is an important clinical goal in treatment of kidney failure, and it is often achieved with a phosphorous poor diet and phosphate binders. Currently this monitoring of the phosphate level is complicated by a poor understanding of how plasma phosphate acutely reacts to a phosphate rich meal. Often patients may have consumed a phosphate rich meal shortly before their blood test is taken, which may have an acute impact on the plasma phosphate level in the blood test and complicated the task of assessing their chronic phosphate levels. To examine this problem, the investigators wish to conduct a randomized cross-over trial, where peritoneal dialysis patients are recruited and randomly assigned to consume either a meal either high or low in phosphate on the first day of trial and the opposite in the second. With blood tests just before and during 5 hours after the meal, the investigators will examine plasma-phosphate levels as well as other blood parameters of importance to the mineral metabolism to determine, whether a meal rich in phosphate causes significant changes in these test parameters compared to a meal poor in phosphate.