The Biochemical Status of Vitamin A and Alpha-tocopherol during Different Stages of Renal Disease and its Relationship to Diabetes.

The status of vitamin A, alpha-tocopherol and retinol binding protein (RBP) was investigated in 34 type 2 diabetic patients with renal impairment (mean serum creatinine 176 micromol/L), 26 type 2 diabetic patients with chronic renal failure (CRF) (mean serum creatinine 629 micromol/L) and 19 non-diabetic patients with CRF. In renal failure patients, the change in response to the dialysis procedure over the time for all the measured parameters was evaluated. Fasting plasma retinol, alpha-carotene, beta-carotene and alpha-tocopherol were determined by high-pressure liquid chromatography. The concentrations of RBP in plasma were determined by a double antibody sandwich enzyme linked immunosorbent assay. Concentrations of retinol, RBP and beta-carotene were significantly higher in diabetic patients with CRF than in diabetic patients with renal impairment or in non-diabetic patients with CRF. A significant decrease was found for the concentrations of beta-carotene (p< 0.003) and RBP (p< 0.003) in response to the dialysis procedure. Retinol/RBP ratio significantly increased with time (p< 0.0004). Serum creatinine concentrations were associated with the increased plasma RBP indicating that RBP may be dependent on renal function and changes in levels of RBP in serum may be used in the assessment of renal function.