CFTR and hypervitaminosis A: Therefore, the question arises whether patients on CFTR modulators should be monitored more closely for vitamin A serum levels in order to avoid the development of hypervitaminosis A. In general, liver damage associated with hypervitaminosis A is well known, but it may be clinically overlooked because the biochemical liver dysfunction in this case is often mild and the morphologic features may also be similar to those of CF-related hepatopathy.