An increased apo A-IV serum concentration of patients with chronic renal failure on hemodialysis

Serum apolipoprotein (apo) A-IV concentration was determined in 20 patients with chronic renal failure on hemodialysis. The mean value of apo A-IV was 33.5 +/- 6.3 mg/dl, that was increased by approximately 3 times compared with that in healthy controls (11.1 +/- 2.7 mg/dl, n = 23). No significant correlation of apo A-IV was observed with the other apolipoproteins (apo A-I, A-II, B, C-II, C-III, and E) levels, serum lipids (TC, TG, and HDL-C) levels, and lipoprotein concentrations in both the patients and the controls. However, apo A-IV was significantly correlated with serum creatinine, BUN, and beta 2-microglobulin levels (p less than 0.05) in the patients. On the other hand, in patients with nephrotic syndrome and in that of a patient with Fanconi's syndrome, apo A-IV was detected in their urine. These results, in turn, suggest from their well-known pathogenesis that apo A-IV can readily transverse the glomerular filter due to its small molecular mass size and that it is also probably taken up and catabolized by renal tubular cells in the same fashion as other low molecular mass proteins. These observations suggest that a decreased glomerular filtration and/or reduced catabolism of apo A-IV by tubular cells may be one of the important causes of the increase in the serum apo A-IV level in patients with chronic renal failure besides a decreased catabolism of chylomicron remnants containing apo A-IV.