[Intestinal lactase and milk consumption before and after gastrectomy].

Intestinal lactase assays before and after a Billroth II procedure for chronic duodenal ulcer did not reveal a significant difference. Postoperative lactose intolerance is due to the loss of pyloric function, causing entrance of lactose into the jejunum at a rate exceeding the hydrolytic capacity of the mucosa if the lactase level is low.