Retinyl ester retention in chronic renal failure. Further evidence for a defect in chylomicron remnant metabolism

The metabolic remnants of triglyceride-rich lipoproteins are atherogenic in man and experimental animals. Particles resembling lipoprotein remnants have been found in plasma from patients with chronic renal failure (CRF). In this study we took advantage of the observation that retinyl esters are transported only by lipoproteins that originate in the intestine, that is, by chylomicrons (CM) and their remnants. To investigate further remnant metabolism in CRF, plasma RE were measured by reverse-phase high performance liquid chromatography in 20 non-diabetic hemodialyzed patients with CRF and 20 hospitalized non-diabetic control subjects 12-15 h after the administration of retinyl ester, 25000 IU orally. Total plasma RE were increased 3-fold in the CRF patients (P less than 0.001). Quantitative analysis of retinoids and lipids in fractions separated by unit-gravity flotation and flocculation in 3% polyvinylpyrrolidone indicated that the plasma RE were not contained among intact CM. Mean plasma retinol in CRF was also elevated consistent with previous observations and the known role of the kidney in retinol-binding protein metabolism. Although postabsorptive RE concentration was correlated positively and significantly with plasma triglyceride concentration in both groups, RE were higher in CRF patients at comparable plasma triglyceride concentrations. These data support the proposal that atherogenic lipoprotein remnants accumulate in the plasma of patients with CRF.