[Special problems of nutritional therapy in chronic kidney insufficiency in the pre-dialysis stage]

The main objectives of medical and nutritional management of patients with chronic renal failure are to slow down the progression of renal disease and to prevent secondary complications due to hypertension, uremic metabolic disturbances, and bone disease. The importance of nutritional measures for this purpose is increasingly recognized. In the setting of vitamin D and calcium deficiency secondary hyperparathyroidism and retention of phosphate result in renal osteodystrophy. An increase in dietary calcium and avoidance of foods rich in phosphate are important. In some patients supplementation of vitamin D3 may be necessary while calcium homeostasis is monitored during follow up. The dietary protein content can influence the severity of the uremic state. Normal or increased consumption of protein may accelerate the progression of renal disease due to the accumulation of nitrogenous products. In addition, uremia itself may cause loss of appetite and thus accumulation of endogenous nitrogen compounds as a result of protein catabolism. Protein restriction under such circumstances may cause malnutrition and an associated increase in morbidity and mortality. Thus, dietary management must consist of individually designed restriction of total protein intake with ingestion of high value protein. This allows balanced nitrogen metabolism with a reduction in circulating uremic toxins.