1. Serum vitamin A, retinol binding protein, prealbumin and transferrin have been studied in chronic renal failure patients receiving maintenance haemodialysis and after renal transplantation.
2. Vitamin A and retinol binding protein were uniformly raised in haemodialysis patients and this was unrelated to the period on dialysis. There was a molar excess of retinol binding protein to both vitamin A and prealbumin as compared with normal individuals.
3. Renal transplantation significantly reduces serum vitamin A and retinol binding protein concentrations but has no effect on prealbumin concentrations. The reduction in vitamin A and retinol binding protein is variable in individual patients and cannot be predicted either by the allograft function or time since transplantation.
4. Several years after transplantation, with normal serum creatinine, both serum vitamin A and retinol binding protein levels may still be greatly increased. Despite the very high vitamin A and retinol binding protein concentrations, the close correlation between the two seen in normal individuals is well maintained.
5. The continuing high vitamin A and retinol binding protein levels in patients with satisfactorily functioning transplants is unexplained.