Serum retinol levels and pulmonary function in children and adolescents with cystic fibrosis

Abstract

Background: It has been suggested that higher serum retinol levels could have protective effects on pulmonary function (PF) in patients with cystic fibrosis (CF). However, serum retinol levels will be transiently decreased during pulmonary exacerbation. Therefore, the extent of chronic pulmonary inflammation should be included when describing the association between PF and serum retinol. We assessed the longitudinal relation between serum retinol, immunoglobulin G (IgG) and PF in paediatric CF patients. Methods: We studied the serum retinol, IgG and forced expiratory volumes in one second (FEV<inf>1</inf>% pred.) of 228 CF patients during a seven-year follow up period. The cross-sectional and longitudinal relations between these variables were assessed. Results: Serum retinol, with medians levels between 1.2 and 1.4μmol/l, were relatively stable, while median serum IgG gradually increased during the age years. The FEV<inf>1</inf>% pred. was longitudinally inversely associated with serum IgG and age, but not with serum retinol. Each g/l increase in serum IgG level was associated with an accelerated yearly decline in FEV<inf>1</inf>% pred. of 0.5% (95% CI -0.8 to -0.1, p=0.008), and each year increase in age was associated with a 1.7% (95% CI -2.1 to -1.3, p=0.000) decline in FEV<inf>1</inf>% pred. This effect was not observed with respect to serum retinol levels (95% CI -1.9 to 2.2, p=0.570). Conclusions: In this large sample of children and adolescents with CF, we found no evidence that higher serum retinol levels had protective effects on PF.