Lactase deficiency

Diarrhea is a common problem that is usually self-limiting and of short duration. Increased accumulations of small intestinal and colonic contents are known to be responsible for producing diarrhea. The former may be caused by increased intestinal secretion which may be enterotoxin-induced, eg, cholera and E. col] or hormone and dmg-induced, eg, caffeine, prostaglandins, and laxatives decreased intestinal absorption because of decreased mucosal surface area, mucosal disease, eg, tropical spme, or osmotic deficiency, eg, disaccharidase or lactase deficiency and rapid transit of contents. An increased accumulation of colonic content may be linked to increased colonic secretion owing to hydroxy fatty acid or bile acids, and exudation, eg, inflammatory bowel disease or amebiasis decreased colonic absorption caused by decreased surface area, mucosal disease, and osmotic factors and rapid transit, eg, irritable bowel syndrome. 

Lactose Milk. May occur in urine during pregnancy. In lactase deficiency, malabsorption leads to diarrhea and flatulence. 

Noninfectious causes of acute diarrhea include drugs and toxins (Table 18-3), laxative abuse, food intolerance, irritable bowel syndrome (IBS), inflammatory bowel disease, ischemic bowel disease, lactase deficiency, Whipple s disease, pernicious anemia, diabetes mellitus, malabsorption, fecal impaction, diverticulosis, and celiac sprue. 

Symptoms of lactase deficiency after ingestion of lactose (milk products) include... 

Galactose intolerance Voriconazole tablets contain lactose and should not be given to patients with rare hereditary problems of galactose intolerance, Lapp lactase deficiency, or glucose-galactose malabsorption. 

Blum, A.L., Haemerli, U.P., and Lorenz-Meyer, H., Is phloridzin or its aglycon the inhibitor of intestinal glucose transport A study in normal and lactase-deficient men, Eur. J. Clin. Invest., 5, 285, 1975. 

The real need for lactose-free milk products is hmited as most lactase-deficient adults can tolerate larger amounts than they are likely to consume. 

There are several forms of intolerance to lactose and galactose. Primary adult lactase deficiency is a normal age-related decrease in lactase activity seen in the majority of adults. Secondary lactase deficiency is a transient state of low enzyme activity following injury to the intestinal mucosa as a result of diseases such as celiac sprue, infectious gastroenteritis, and protein-calorie malnutrition. The last two states are common conditions (Dahlqvist 1983). 

Congenital lactase deficiency is extremely rare. This condition is due to a genetic defect in which lactase enzyme is absent from birth. 

The question has arisen of whether lactase deficiency is inherited or acquired. In most mammals, lactase declines to low levels or is entirely absent after weaning. It would seem entirely feasible that it could be an acquired characteristic in people who customarily do not drink milk. 

Low lactase activity has been suggested as a factor leading to osteoporosis as a result of either reduced calcium intake or reduced calcium absorption. However, results are conflicting and further studies will be necessary to resolve this question (Paige and Bayless 1981). The relationship between irritable bowel syndrome and lactase deficiency is still unclear, but hypolactasia does not appear to be a major problem in patients with this condition (Paige and Bayless 1981). 

Bayless, T. M. and Rosensweig. 1966. A racial difference in incidence of lactase deficiency. A survey of milk intolerance and lactase deficiency in healthy adult males. JAMA 197, 968-972. 

Newcomer, A. D. and McGill, D. B. 1984A. Clinical consequences of lactase deficiency. 

Newcomer, A. D., Park, H. S., O Brien, P. C. and McGill, D. B. 1983. Response of patients with irritable bowel syndrome and lactase deficiency using unfermented acidophilus milk. Am. J. Clin. Nutr. 38, 257-263. 

Carbohydrate abnormalities, such as renal glycosuria (a transport defect), pentosuria (enzyme deficiency, xylitol dehydrogenase I. lactase deficiencies, fructose intolerance, galactosemia, galacloki-nase deficiency, oxalosis, and several glycogenoses (von Gierke s, Forbes . Andersen s, Hers s. and Tarui s diseases). 

Savaiano, D. A., AbouElAnour, A., Smith, D. E., and Levitt, M. D. (1984). Lactose malabsorption from yogurt, pasteurized yogurt, sweet acidophilus milk, and cultured milk in lactase-deficient individuals. Am. J. Clin. Nutr. 40(6), 1219-1223. 

The SNPs identified and a role for differential activity of an enhancer in lactase persis-tence/nonpersistence do not, however, explain how those individuals with the genotype leading to adult lactase nonpersistence were able to produce sufficient lactase in infancy. There are developmental questions that remain to be answered. Congenital lactase deficiency has been localized to a separate region, also on chromosome 2q21 but not within the LCT gene (Jarvela et al., 1998). 

Jarvela I, Enattah NS, Kokkonen J, et al. Assignment of the locus for congenital lactase deficiency to 2q21,in the vicinity but separate from the lactase-phlorizin hydrolase gene. Am J Hum Genet 63 1078-1085,1998. 

Osmotic diarrhoea occurs when a non-absorbable substance draws fluid into the intestine by osmosis, for example lactase deficiency, when unabsorbed lactose remains in the intestine. This type of problem also occurs in malabsorption disorders, for example in celiac disease. 

Insufficient digestive agents Biliary obstruction Chronic liver failure Chronic pancreatitis Cystic fibrosis Lactase deficiency Pancreatic cancer Pancreatic resection Sucrase-isomaltase deficiency... 

Caution in proarrhythmic conditions, electrolyte abnormalities, galactose intolerance, lactase deficiency, hematologic malignancy... 

Phenylketonuria Alcaptonuria Hyperammonemia I Hyperammonemia II McArdle s syndrome Hypophosphatasia Congenital lactase deficiency Hereditary fructose intolerance Gout... 

Thousands of diseases related to deficient or defective enzymes occur, many of which are rare. For example, in phenylketonuria (which has an incidence of 1 in 10,000 births in whites and Asians), the enzyme phenylalanine hydroxylase, which converts phenylalanine to tyrosine, is deficient. Phenylalanine accumulates, and tyrosine becomes an essential amino acid that is required in the diet. Mental retardation is a result of metabolic derangement. A more common problem is lactase deficiency, which occurs in 69% to 90% of American Indians, blacks, and Asians, and in 10% of whites. Lactose is not digested normally and accumulates in the gut where it is metabolized by bacteria. Bloating, abdominal cramps, and watery diarrhea result. 

Intestinal lactase deficiency is a common condition in which lactose cannot be digested and is oxidized by bacteria in the gut, producing gas, bloating, and watery diarrhea. 

A pregnant woman who has a lactase deficiency and cannot tolerate milk in her diet is concerned that she will not be able to produce milk of sufficient caloric value to nourish her baby. She should be advised that... 

A woman with a lactase deficiency who eats no dairy products... 

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