SALT LAKE CITY — For children with cystic fibrosis and pancreatic insufficiency, vitamin A supplements are sometimes too much of a good thing, Dr. Rose C. Graham-Maar said at the annual meeting of the North American Society for Pediatric Gastroenterology, Hepatology, and Nutrition. Guidelines in 2002 recommended vitamin A supplementation for the 90% of cystic fibrosis patients who have pancreatic insufficiency, which puts them at risk for vitamin A malabsorption.
A study of 73 preadolescents aged 8–12 years with cystic fibrosis found that they took high doses of supplementary vitamin A, especially preformed retinol, which is more likely than provitamin A to cause liver or bone toxicity. The patients had higher serum retinol concentrations, compared with 663 children of similar age included in the National Health and Nutrition Examination Survey, said Dr. Graham-Maar, of the Children's Hospital of Philadelphia, and her associates.
Daily vitamin A intake exceeded recommendations for people with cystic fibrosis and pancreatic insufficiency in 36 patients (49%), and were above the upper limit of daily recommended intake for the general population in 64 patients (88%). “The doses in these kids are higher than we think they need,” although there's no clinical proof yet of harm, Dr. Graham-Maar said in an interview.
There are no good clinical measures, short of a liver biopsy, to assess vitamin A toxicity, she noted. Even if serum levels are normal, excess vitamin A in the body can cause liver disease or osteoporosis, which “we see in kids with cystic fibrosis on a fairly regular basis.”
Excess vitamin A ingestion can cause hepatic fibrosis, cirrhosis, liver failure, osteoporosis, anorexia, and weight loss—all problems seen in cystic fibrosis, confounding whether the disease or other factors contribute to these problems.