HOME PARENTERAL-NUTRITION AND VITAMIN-B-12 STATUS

The vitamin B-12 status of 20 subjects who were on home parenteral nut rition after surgical or functional small bowel resection and were giv en 1000 mu g cyanocobalamin every 3 mo was studied by comparing their plasma vitamin B-12, homocysteine (HS), and methylmalonic acid (MMA) c oncentrations. The plasma vitamin B-12 concentration (median 145 pmol/ L, 95% confidence interval: 123-217) was subnormal in four cases and b orderline in four others. In the ''low B-12'' group, the concentration s of the markers of vitamin B-12 deficiency were in the normal range: HS 10.7 mu mol/L (8.0-12.3); and MMA, 0.15 mu mol/L (0.09-0.19). Refer ences values were HS, 10.0 mu mol/L (9.4-12.6); and MMA, 0.16 mu mol/L (0.10-0.19). Thus, there were no metabolic signs of vitamin B-12 defi ciency in these subjects on parenteral nutrition, despite the fact tha t their plasma vitamin B-12 levels were low. Analysis of individual da ta showed that the four patients with low circulating B-12 had markers of intracellular vitamin B-12 deficiency in the normal range. (C) Els evier Science Inc. 1997.