Calcium malabsorption and absence of bone decalcination following intestinal shunt operation for obesity. A comparison of two types of operation.

Calcium absorption was studied in 23 patients before and one year after intestinal shunt operation for obesity. It decreased from 23 to 12% (p less than 0.02) after surgery, when the jejunum/ileum ratio was 36cm/12cm [type I], and only from 19 to 16% (p greater than 0.05), when the ratio was 12cm/36cm [type III]. It is suggested that the difference is due to variation in absorptive surface in the distal half of the small intestine and to a minor degree to change in external pancreatic function, bile acid metabolism, and fat digestion. Bone mineral content was lower in 37 obese than in normal subjects and underwent only minor changes (p greater than 0.01) 3 and 12 months after surgery, possible because of postoperative daily calcium and vitamin-D substitution.