Objective: To explore the serum retinol and retinol binding protein-4 (RBP(4)) levels in patients with chronic obstructive pulmonary disease (COPD) and to investigate their relationship with the nutritional status.
Methods: The serum retinol level was determined by high-performance liquid chromatography (HPLC) in 110 outpatients with stable COPD during Sept. 2006 to Sept. 2007, and 90 healthy volunteers served as the controls. The serum RBP(4) level in 62 stable COPD outpatients and 20 healthy controls was measured by enzyme-linked immunosorbent assay (ELISA). Associated factors with the serum retinol and RBP(4) levels were analyzed. t-test and one-way ANOVA were used for the statistic analysis.
Results: The serum retinol and RBP(4) levels in COPD patients [(275 +/- 11) microg/L and (7.4 +/- 2.6) mg/L respectively] were significantly lower than those in the healthy controls [(338 +/- 13) microg/L and (11.4 +/- 4.1) mg/L respectively, t = 3.650, t = 4.155 and all P < 0.01]. The serum retinol and RBP(4) levels in COPD patients with malnutrition [(246 +/- 18) microg/L and (6.4 +/- 1.0) mg/L individually] were significantly lower than those in COPD patients without malnutrition [(290 +/- 14) microg/L and (8.2 +/- 3.2) mg/L individually, q = 3.35, P < 0.05 and q = 10.22, P < 0.01 respectively], but the levels of serum retinol and RBP(4) in COPD patients without malnutrition were significantly lower than those in the healthy controls [(338 +/- 13) microg/L and (11.4 +/- 4.1) mg/L respectively, q = 2.26, P < 0.05 and q = 4.82, P < 0.01 respectively]. In a multiple stepwise regression analysis, only body mass index and mid arm circumference were independently associated with the serum retinal level.
Conclusion: In patients with stable COPD, the levels of serum retinol and RBP(4) were significantly decreased, which was associated with the nutritional status.