Removal of intracellular waste products by hemofiltration

Because the total amount of waste products removed by hemofiltration can be measured exactly, it was divided into two components, that removed from the extracellular compartment and that removed from the intracellular compartment, using inulin as a marker for extracellular fluid in five uremic patients treated with hemofiltration in the postdilution mode. The amount removed from the extracellular compartment as a proportion to the total amount removed from the whole body by hemofiltration was 86.5% +/- 10.6% for guanidinosuccinic acid, 69.1% +/- 15.6% for sodium, 59.4% +/- 3.3% for uric acid, 56.4% +/- 2.1% for inorganic phosphate, 45.6% +/- 5.3% for creatinine, 43.1% +/- 7.2% for potassium, 42.9% +/- 3.1% for guanidinoacetic acid, 42.5% +/- 7.5% for methylguanidine, 37.2% +/- 8.4% for chloride, 36.3% +/- 2.8% for urea, and 6.9% +/- 2.9% for glucose. These results show that extracellular substances such as sodium and guanidinosuccinic acid were removed mainly from the extracellular compartment. On the other hand, glucose was removed only from the intracellular compartment, since blood glucose level is regulated. Although uric acid, inorganic phosphate, creatinine, potassium, guanidinoacetic acid, and methylguanidine are intracellular substances, they accumulated also in the extracellular fluid in renal failure, and were removed from both compartments, intracellular as well as extracellular, by hemofiltration.