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β-d-galactosidase; an enzyme in the intestinal mucosa that hydrolyzes lactose, producing glucose and galactose.
lactase deficiency a deficiency of intestinal lactase, which causes abdominal distention and cramping and often diarrhea when milk is drunk. The condition is usually hereditary with an onset between infancy and early adulthood, and is more common in Blacks, American Indians, and East Asians (70 to 90 per cent) than in Whites (10 to 15 per cent). It may also occur secondary to massive small bowel resection or to diseases involving the mucosa, such as celiac disease, Crohn's disease, tropical sprue, and ulcerative colitis.
lactase deficiency/lac·tase de·fi·cien·cy/ reduced or absent lactase activity in the intestinal mucosa; the hereditary adult form is the normal state in most populations other than white Northern Europeans and may be characterized by abdominal pain, flatulence, and diarrhea after milk ingestion (lactose intolerance); the rare congenital form (congenital lactose intolerance) is characterized by diarrhea, vomiting, and failure to thrive.
an inherited abnormality in which the amount of the digestive enzyme lactase is inadequate for the normal digestion of milk products, resulting in lactose intolerance, the inability to digest lactose (except for the bacterial breakdown of lactose in the large intestine). Lactose intolerance usually doesn't appear until 4 or 5 years of age, begins gradually, and persists throughout life. In adults a relative deficiency may appear as a natural process of aging; it occurs more frequently in persons of Asiatic, Native American, and African heritage. A lactase inadequacy also may result from subtotal gastrectomy and may be secondary to any disease of the small intestine in which structural changes occur, such as tropical sprue, ulcerative colitis, infectious hepatitis, and kwashiorkor; severe malnutrition; or some types of antibiotic therapy. See also lactose intolerance.
lactose intoleranceA term that encompasses an array of adverse responses to consumption of non-human milk, in particular the inability to digest lactose, a sugar in milk and many dairy products. Up to 75% of adults have a decrease in lactase with age, which presents clinically as abdominal bloating, cramps, flatulence, diarrhea, nausea and/or vomiting, and borborygmi (a rumbling noise of the intestines).
d-galactosidase; an enzyme in the intestinal mucosa that hydrolyzes lactose, producing glucose and galactose.
a deficiency of intestinal lactase, which causes abdominal distention and cramping and often diarrhea when milk is drunk.