The effect of continuous venovenous hemofiltration (CVVH) on serum retinol and retinol binding protein concentrations in the critically ill

Introduction. The functions of Vitamin A include glycoprotein synthesis, epithelial growth and differentiation, reproduction, dark adaptation and vision. Retinol is the parent compound of Vitamin A and Retinol Binding Protein(RBP) is the major transport vehicle for Vitamin A. RBP (MW=21,000) is synthesized and secreted by the liver. Levels of Vitamin A, RBP and Pre -albumin are decreased in liver disease. The effect of hemofiltration on RBP levels in the critically ill is unknown. This study was designed to determine if CVVH has a significant effect on serum levels of retinol and RBP in surgical ICU patients. Methods. During a 6 month period, 15 patients on CVVH in the surgical ICU were studied. Hemofiltration using a Renaflo II Hemofilter (HF 700, Renal Systems, Minn., MN) was initiated by the ICU attending physician when indicated. Patients receiving multivitamins via TPN were recorded. Blood samples were taken prior to the initiation of CVVH then at 6, 24, and 72 hours during hemofiltration. Retinol was measured via HPLC (Labcorp Holdings, Raritan, NJ) and RBP via chemilumminescence (Nichols Institute, CA). Results. Data are presented as the mean ± SEM. Baseline 6 hrs 24 hrs 72 hrs Retinol (mcg/dl) 46 ± 13 36 ± 06 35 ± 07 41 ± 13 RBP (mg/dl) 4.0 ± 0.7 3.6 ± 0.7 3.7 ± 0.6 3.5 ± 0.6 A p<.05 was considered significant. Conclusions. This study demonstrates no significant reduction in retinol or RBP levels after the initiation of CVVH. The initial decrease observed in serum retinol may be secondary to adherence to the hemofilter. These findings demonstrate that serum levels of Vitamin A are not significantly reduced following three days of CVVH.