Objective: The aim of the present study was to explore the relation between lung function and serum retinol (SR) in cystic fibrosis (CF) patients.
Methods: This was a cross-sectional study conducted in a group of 98 young patients with CF (6.8-22.3 years), after the exclusion of those with pulmonary exacerbation, vitamin A deficiency, or other risks, from an initial group of 124 cases.
Results: Data of forced expiratory volume in 1 second (FEV₁) were widely scattered (87.7% ± 16.9%). These were similar in the 78 pancreatic insufficient and 11 pancreatic sufficient patients. SR (56.6 ± 18.4 μg/dL) was >2.5th percentile of healthy people in the whole group, although 31 patients were situated above the 97.5th percentile (higher value: 110 μg/dL). The FEV₁ was noticeably higher in these than in those within the normal range (93.6 ± 14.0 vs 85.0 ± 17.6 μg/dL; P < 0.05). The z score of SR correlated positively with FEV₁ (r = 0.364; P = 0.000), after adjusting data for sex, age, body mass index, and pancreatic function. The odds ratio for a FEV₁ >80% is 3.78 in patients with SR above the 97.5th percentile, versus only 0.26 in those within the normal range. There were no cases with retinol toxicity.
Conclusions: FEV₁ of young patients with CF correlates positively with SR, regardless of age, pancreatic function, or nutritional condition. Those with a moderately high retinol (up to 110 μg/dL) maintain the best respiratory function (FEV₁ ≥80% in >90% of them) without any signs of toxicity.