Vitamin A status and its determinants in patients with cystic fibrosis.

Background: Routine administration of vitamin A, recommended in CF patients, can help to prevent its deficiency. However, high vitamin A supplementation may lead to its excessive level and possible toxicity. Therefore, the aim of the present study was to assess the status of vitamin A and the determinants of its body resources in CF patients.

Methods: In 196 CF patients aged from 4 months to 47 years, the following parameters  were analysed: nutritional status (standardized body weight and height, serum albumin concentration) and clinical expression of disease (lung function - spirometry; biochemical markers of liver function - ALT, AST, GGT; respiratory tract colonization by Pseudomonas aeruginosa; diabetes; cirrhosis, non-cirrhotic liver disease; exocrine pancreatic function - fecal elastase-1 concentration; blood clotting -  INR  and  vitamin  A supplementation).

Results: Median vitamin A concentration in the study group was 383.0 ng/ml (1st-3rd quartile: 316.5-457.0). Vitamin A deficiency was found in 32 (16.3%) subjects studied. Vitamin A concentrations above the reference range were observed only in 3 (1.5%) CF patients. CF patients with vitamin A deficiency were significantly older and had lower values of FEV1 compared to CF subjects with normal vitamin A status. Moreover, vitamin A deficiency occurred more frequently in CF patients with diabetes, Pseudomonas aeruginosa colo- nization, worse lung function and in those without vitamin A supplementation. However, in multiple linear regression analyses, none of the independent variables was documented to be important for predicting vita- min A status.

Conclusions: Vitamin A body resources in CF patients are mostly normal. Moreover, there are no good de- terminants of vitamin A status in these patients. Further studies targeted at exploring potential toxicity and deficiencies of vitamin A in CF patients are needed.