Vitamin D binding protein, a new nutritional marker in cystic fibrosis patients

Background: Vitamin D binding protein (DBP) is a multifunctional transport protein with a decreased serum concentration in cystic fibrosis (CF). The present study investigates the importance of DBP and its role as an alternative nutritional marker in CF. Methods: DBP phenotypes of 116 CF patients were determined electrophoretically. Serum DBP was measured by immunonephelometry. Parathormone was assessed by an immunoradiometric assay. Serum 25OH vitamin D3, 1,25(OH)2 vitamin D3 and leptin concentrations were determined by a radioimmunoassay. Serum α-tocopherol was measured by HPLC. Routine chemistry parameters were assessed using commercial methods. The Prognostic Inflammatory and Nutritional Index was calculated. Results: Decreased serum DBP concentrations were observed in the CF group. Total cholesterol, low-density lipoprotein (LDL)-cholesterol, triglyceride concentration, α-tocopherol and a low nutritional status correlated positively with DBP. Lipoprotein precipitation demonstrated a partial presence of DBP in very-low-density lipoprotein and LDL. Furthermore, DBP was positively correlated with serum leptin concentration. Conclusions: The present study demonstrates a positive correlation between DBP and serum lipids. Serum DBP concentration can be considered as a nutritional marker (especially for lipids). Clin Chem Lab Med 2008;46:365–70.