EVIDENCE THAT REDUCED LIPOPROTEIN-LIPASE ACTIVITY IS NOT A PRIMARY PATHOGENETIC FACTOR FOR HYPERTRIGLYCERIDEMIA IN RENAL-FAILURE

The aim of the study was to document postheparin plasma lipoprotein lipase (LPL) and hepatic lipase activities and relate these to serum lipid, lipoprotein and apolipoprotein concentrations in 85 patients with kidney function ranging from normal to dialysis dependency. Strict selection criteria were applied in order to exclude conditions other than renal failure which may influence lipid metabolism. Stress was laid on minimizing proteinuria and inflammatory activity. The changes in the lipoprotein pattern were numerically strikingly modest compared to those previously reported. This probably reflected the intention to elucidate the contribution of reduced renal function as such to the dyslipoproteinemia of renal failure, a condition often associated with confounding factors. Significant increases in serum concentrations of triglycerides and apolipoprotein CIII were already observed in moderate renal failure, whereas serum concentrations of high density lipoprotein cholesterol and plasma LPL activities were decreased only in severe renal failure. Plasma LPL activities were not significantly reduced in hemodialysis patients (probably due to anticoagulation with low molecular weight heparin), but serum concentrations of triglycerides and apolipoprotein CIII were significantly increased. A multiple regression analysis, taking glomerular filtration rate, LPL and apolipoprotein CIII into account, showed that both plasma LPL activity and serum apolipoprotein CIII concentration independently predicted serum triglyceride concentration. However, serum apolipoprotein CIII concentration was a much stronger predictor than plasma LPL activity. Thus, a decrease in LPL activity does not seem to be a prerequisite for the hypertriglyceridemia of uremia, but it probably accentuates this condition. The basal disturbance in the lipoprotein metabolism in renal failure might be poor substrate characteristics of triglyceride-rich lipoproteins for LPL, possibly due to alterations in apolipoprotein composition. Plasma hepatic lipase activities were independent of renal function.