The effect of systemic heparinization on plasma lipoproteins and toxicity in patients on hemodialysis and continuous ambulatory peritoneal dialysis

Lipoprotein lipase disturbances induced by uremia and hemodialysis

Factors such as malnutrition, physical inactivity, uremic toxins, and inflammation are known to influence the activity of lipoprotein lipase (LPL), an important enzyme in metabolism of blood lipids. In patients with chronic kidney disease these factors are common and may result in a decreased LPL activity. This is particularly so in patients on hemodialysis. Further, during each dialysis treatment, the use of heparin (or low molecular weight heparin) induces a release of LPL from its normal binding sites at the plasma membrane of endothelial cells. This results in an increased degradation of the enzyme and a relative lack of LPL activity for up to 10 hours from the start of the dialysis. Thus, the use of conventional anticoagulation for hemodialysis, in addition to the consequences of the uremic state, may cause a severe functional deficiency of LPL. This in turn may have deleterious effects on energy metabolism and may contribute to the increased risk for cardiovascular disease in this vulnerable group of patients.

Kinetics of peritoneal protein loss during CAPD: II. Lipoprotein leakage and its impact on plasma lipid levels

We quantified the plasma levels and peritoneal loss of lipids and lipoproteins, and studied the composition of plasma and effluent lipoproteins in 16 patients on CAPD (5 females and 11 males, 18 to 76 years old). Five patients were studied prospectively (at 0, 1, 3 and 6 months) and 11 patients at 6 to 58 months on CAPD (N = 30). Elevated levels of plasma VLDL and reduced levels of plasma HDL were maintained in these patients throughout 58 months of CAPD, whereas the initially increased LDL levels showed a tendency towards normalization. All plasma lipoproteins (VLDL, IDL, LDL and HDL) were present in the peritoneal effluent. The lipoproteins isolated from plasma and peritoneal fluid shared a similar lipid and apolipoprotein composition. The peritoneal transport characteristics of plasma lipoproteins were similar to other plasma macromolecules. Their clearance correlated with their molecular mass, plasma concentration and dwell time, but was not affected by duration of CAPD treatment. The plasma lipid and lipoprotein levels were unaffected by the rate of glucose absorption. The peritoneal protein clearance correlated positively with plasma levels of triglyceride and LDL, and negatively with plasma HDL. An inverse correlation was observed also between plasma levels of HDL and its peritoneal clearance (r = -0.393, P less than 0.025, N = 30). The continuous peritoneal loss of HDL and the hypertriglyceridemia were found to contribute most to the persistent low plasma levels of HDL in CAPD patients, and thus may lead to the accelerated atherosclerosis observed in these patients.

Changes of serum lipids and lipoproteins during haemodialysis treatment in dialysed chronic uraemic patients

Changes of serum lipids and lipoproteins were determined quantitatively before and after haemodialysis in chronic uraemic patients. Serum beta-lipoprotein significantly decreased due to haemodialysis, while alpha-lipoprotein and the FFA level significantly increased. Slight correlations were observed between the applied transmembrane pressure and the serum concentration of FFA, HDL-cholesterol or total cholesterol levels. Hyper-beta-lipoproteinemia was found in 70.9 per cent and Frederickson-HLP in 33.3% of the haemodialyzed chronic uraemic patients.