Serum concentration of cobalamines during total parenteral nutrition in Crohn's disease.

The vitamin B12 status was assessed by measuring the fasting serum (S-) concentration of cobalamines in a consecutive series of 12 patients with Crohn's disease (CD) given total parenteral nutrition (TPN)--nil per os--for between 21 and 97 days (mean, 49 days). At introduction of TPN the S-cobalamine concentration was less than 300 pmol/liter in four patients (group I) and more than 300 pmol/liter in eight (group II). Each day during TPN fat- and water-soluble vitamins, including 2 micrograms of cyanocobalamin, were given. In group I there was a small increase in the S-cobalamine level during the first 2 to 4 weeks of TPN, whereas in group II the values approached the middle of the reference range (190-680 pmol/liter) after 6 to 8 weeks of TPN. It would thus appear that the vitamin regimen studied, including 2 micrograms of cyanocobalamin per 24 hr, is able to maintain the S-cobalamine concentration within the reference range during 6 to 8 weeks of TPN in CD patients with no evidence of vitamin B12 deficiency, and to prevent the development of vitamin B12 deficiency during 2 to 4 weeks of TPN in CD patients with a S-cobalamine level initially below 300 pmol/liter.