Analysis of the Factors Contributing to Serum Retinol Binding Protein and Transthyretin Levels in Japanese Adults

Abstract

We examined various factors possibly related to metabolic syndrome, particularly focusing on nutritional assessment proteins such as retinol binding protein (RBP) and transthyretin (TTR), and remnant lipoproteins. Fasting serum lipid was analyzed in 58 Japanese adult volunteers (33 men and 25 women, 42.5 +/- 10.1 years old). The lipid profiles of the subjects were classified by lipoprotein polyacrylamide gel electrophoretic patterns into Types S (n = 10), A (n = 37), and N (n = 11), according to the method described in Internal Medicine 42: 244, 2003. RBP and TTR were significantly higher in Type N than in Types S and A. In multivariate analysis, RBP was accounted for by remnant-like particle-triglyceride (RLP-TG), interleukin 6, body mass index and low-density lipoprotein (LDL)-cholesterol (adjusted R2 = 0.621). TTR was accounted for by lipoprotein(a), adiponectin and RLP-TG (adjusted R2 = 0.415). Malondialdehyde-LDL was significantly accounted for by LDL-cholesterol and RLP-cholesterol (adjusted R2 = 0.601). Lipoprotein(a) and LDL-cholesterol were independent variables for oxidized LDL antigen (adjusted R2 = 0.620). High-sensitivity C-reactive protein was accounted for by interleukin 6, immunoreactive insulin and oxidized LDL antigen (adjusted R2 = 0.361). Uric acid and body mass index were independent variables for adiponectin (adjusted R2 = 0.429). RBP and TTR may be useful as convenient and simple clinical markers of overnutrition and possibly of metabolic syndrome.