The effect of LDL apheresis on the lipid profile of nephrotic patients
Clinical Aim:- To study the safety and efficacy of LDL apheresis in nephrotic patients and to assess the impact of applying a cholesterol "clamp" on the progression of renal disease. Protocol:- 20 patients all with a biopsy proven diagnosis were recruited. Patients were entered into 2 groups using the minimisation technique after scoring for GFR, age, sex, level of proteinuria and presence of concurrent immunosuppression. Group A (n=11) received LDL apheresis in addition to Simvastatin therapy. 12-20 treatments were given to clamp the cholesterol at or below 6.5mmol/l. Group B (n=9) received conventional lipid lowering drug therapy (Simvastatin) only. 1/Cr plots were used to asses progression of disease. Inulin GFR was also measured at entry and at 6 monthly intervals. 24 hour proteinuria, haematology, biochemistry and lipid measurements were made monthly. Patient follow up was for a mean of 17.75 months (SD 7.8). Results:- There was a significant reduction in Total and LDL cholesterol and Triglycerides from baseline values in the apheresis group, for 18 and 15 months respectively. In spite of this sustained lipid "clamp" there was no significant difference in proteinuria or 1/Cr plot. Laboratory Studies 1) Lipid peroxidation was measured by diene conjugation. The methodology of this assay was extensively studied and modified to optimise its reproducibility and accuracy. Nephrotic patients did not exhibit LDL with a shortened lag time, but rate and extent of oxidation was affected by treatment. 2) Anti-oxidant status of patients pre and post LDL apheresis and endogenous levels of both groups were assessed. Apheresis did not adversely affect antioxidant profile. 3) The patients were phenotyped and genotyped for apoE polymorphism. There was an excess of the E4 allele compared to the general population.