Fibrosis Other GI Disorders

Plasma vitamin A and RBP levels have been investigated in patients with cystic fibrosis of the pancreas (Smith et al., 1972 Knopfle et al., 1975 Palin et al, 1979). Plasma vitamin A and RBP levels have been found to be lower than normal in patients with cystic fibrosis, despite the administration of oral vitamin A supplements adequate to maintain normal hepatic stores. In one study (Smith et al., 1972), the plasma vitamin A transport system was studied in 43 patients with cystic fibrosis receiving oral supplements of vitamin A and in 95 normal control subjects of a similar age range. The mean plasma concentrations of vitamin A and RBP were significantly lower in the patients than in the controls. Moreover, in cystic fibrosis patients each component of the transport system failed to show the normal age-related rise. It is not known whether these abnormalities of the retinol transport system are primary or secondary features of cystic fibrosis the abnormalities may, however, play a role in the pathophysiology of the disease. 

Serum RBP and vitamin A levels have also been studied in patients with intestinal disorders and fat malabsorption. Although some patients with such disorders show low plasma retinol and RBP levels (Vahlquist et al., 1978a), in other studies normal RBP levels were found in patients with malabsorption and steatorrhea (Smith and Lindenbaum, 1974 Prellwitz et al., 1974). It can be anticipated that the effects of a given disorder would depend on the nature, severity, and duration of the disease. 

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