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General Reference ⬇

Nejm 1984;310:42

Pathophys and Cause ⬆ ⬇

Cause:Genetic

Pathophys:Mucosal cell deficiency of invertases lactase and sucrase-isomaltase. Diarrhea from osmotic effect, bacterial degradation of these sugars to lactic acid, and steatorrhea

Epidemiology ⬆ ⬇

Lactase deficiency discovered in Holland during World War II when babies with it improved during milk shortages; present in 80% blacks (Nejm 1975;292:1156), 10% Caucasians (Nejm 1967;276:1283), 100% Asians, in 25% of US adults, 75% of all other adults (Nejm 1995;333:1)

Sucrase-isomaltase deficiency (Nejm 1987;316:1306) in 0.2% of US population, 10% of Greenland Inuit

Signs and Symptoms ⬆ ⬇

Sx:Osmotic diarrhea; sucrose or milk intolerance causes bloating and cramps; most common cause of recurrent abdominal pain in children (Nejm 1979;300:1449)

Course ⬆ ⬇

Decreasing tolerance as patient ages from 1-11 yr (Nejm 1967;276:1283)

Complications ⬆ ⬇

r/o milk allergy (Food Allergies)

Lab and Xray ⬆ ⬇

Lab:

Chem:Lactose tolerance by breath test; or by giving 50 gm lactose po and do with hourly blood sugars over 3 h; a normal person should increase blood sugar by 20 mg % if not diabetic

Stool:Elevated lactic acid, lowered pH (test after a milkshake)

Treatment ⬆

Rx:Withhold milk and/or malt and/or sucrose, or prepare food with or add lactase to milk before feeding although 250 cc (8 oz) milk qd is generally tolerated (Nejm 1995;333:1); yogurt may be tolerated (Nejm 1984;310:42). Baker's yeast po with sucrose decrease sx (Nejm 1987;316:1306)