Calcium, phosphorus, magnesium, zinc, and nitrogen balance in patients with severe short bowel syndrome

Abstract

Needs for parenteral supply of calcium, phosphorus, magnesium, zinc, and nitrogen to patients who require long-term parenteral nutrition because of short bowel syndrome, were estimated by balance studies. The nine patients studied had 30 to 200 cm remaining small intestine. Six patients had jejunostomy and three had at least half of the colon in function. The patients had a normal oral intake, which supplied 17 to 27 mmole calcium, 29 to 56 mmole phosphorus, 8 to 17 mmole magnesium, 94 to 184 µmole zinc, and 9 to 16 g nitrogen/day. Most patients had a net loss of calcium in the stools of 1 to 3 mmole/day, but ⅔ attained positive calcium balance by parenteral supply of 9 to 11 mmole calcium/day. Net absorption of magnesium was extremely low or slightly negative (−12 to 5%, median: −2% of the dietary intake). Positive magnesium balance was achieved by parenteral supply of 7 to 15 mmole magnesium/day. Net absorption of zinc differed considerably inversely related to parenteral zinc supply (−92 to 20%, median: −7% of the dietary zinc), but was in no patient sufficient to maintain normal zinc homeostasis. Optimal parenteral zinc supply was estimated to 70 to 100 µmole/day. In contrast the patients had a fairly well preserved net absorption of phosphorus (11 to 49%, median: 32% of the dietary intake) and of nitrogen (21 to 66%, median: 52% of the dietary nitrogen). We conclude that a normal oral intake in patients, who require long-term parenteral nutrition because of short bowel, reduces the need for parenteral nitrogen supply with at least 50% and may render parenteral phosphorus supply superfluous. Parenteral supply of calcium, magnesium, and zinc, however, seems indispensable in all or nearly all patients.