Defeciency of lactase in the brush border causes lactose intolerance.
Symptoms:
Bloating, flatulence, cramps and diarrhea after ingestion of food containing lactose
Lactose intolerance tests 1) positive lactose hydrogen breath test( increased breath hydrogen level after ingestion of lactose due to bacteria carbohydrate metabolism)
2) positive stool test for reducing substances
3) low stool ph( due to fermentation products)
4) increased stool osmotic gap( > 50 mOsm/kg)
