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Disaccharidase deficiency syndromes

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Its cause is the lack or insufficiency in the secretion of  disaccharidases at the enteral level.
The deficit of disaccharidase may be:
  • congenital (the congenital lactase deficiency :the newborn does not tolerate the milk immediately after birth; congenital deficiency; maltase or trehalase).
  • asquired during life-time; it may be transient or definitive (the most frequent is the lactase deficit, with the milk intolerance of the adult


The absence or decreasing of disaccharidase from the intestine will make impossible the dividing of disaccharidase into monosaccharidase and their absorption. The unabsorbed disaccharide determines a growth in the intraluminal osmolarity, with transferring of water into the lumen and increasing the volume of intestinal content. At the same time, the stimulation of intestinal osmo-and chemoreceptors will produce prokinetic chemical mediators (serotonins, bradikinine).

Lactase deficiency


The populations that do not traditionally consume milk have a lactase deficiency of 40%-90% in the adults.
Populations that have been growing animals have a quite low percent of lactase deficiency in the adult (5-15%).
Therefore, there is a congenital deficit of lactase, which manifests it self immediately after birth, by diarrhea.


At the microscopic examination, the intestinal mucosa has a normal aspect, including the villi and the “brush margin”. Using some immunohistochemical techniques it can be discovered the decreasing or absence of the enzymatic material at the level of “brush margin”.
The changing of the basic disease appear only in the secondary lactase deficiencies.

Clinical features

Typically, after milk or dairy products intake, the patient with lactase deficit presents after a few minutes: bloating, bubbling, explosive liquid stools, flatulence.


Starting from the evident clinical signs or clinical suspicion, an ambulatory alimentary test may be performed, asking the patient to ingest250-300 ml milk, on an empty stomach, without other aliments, and check-aout the effect for 2-3 hours. If the clinical signs described above appear, the diagnosis is clear.
The lactose tolerance test,which consists in 3 phases: clinical, biological and radiological. We determine the patients glycemia, and then the patient takes 50g lactose in 400 ml water and a barium sulphate bottle. The glycemia is measured at 30, 60, 90 and 120 minutes and an abdominal X-ray is performed after 1 hour.

Interpretation of results

  • clinical: the apparition of diarrhea, with flatulence, bubbling after 20-30 minutes of lactose ingestion indicates a positive clinical test.
  • biological: if glycemia does not growth with more than 25% of the initial value is considered a positive test
  • radiological: the dilution of barium mass, aeroenteria with distention of bowels and a very accelerated intestinal transit; usually, the barium column gets into the colon in one hour.

The respiratory tests of determination of lactase deficit are very modern, but they require relatively complex devices. The marking of lactose with C14 is used,with determination of marked CO2 in the exhaled air, or only lactose, with determination of H2 in the exhaled air (a growth of H2 exhaled > 20 ppm at 3-6 hours from ingestion suggests a lactase deficiency).

The lactase determination in the biopsy

Differential diagnosis

  • milk allergy
  • the osmotic intolerance to milk
  • psychogenic intolerance to milk


The evolution of the disease in the adult is favorable, since most patients restrain the alimentation them selves, avoiding dairy products. In some cases mostly undiagnosed, may appear multiple conditionings, with prolonged diarrhea, sometimes even malabsorbtion.


Treatment clearly dietary-it consists in the reduction or complete elimination of milk and dairy products from the alimentation.
Milk without lactose may be used . For  the adults with the apparition of food containing lactase such as Lactaid.

In the sucrase deficit sugar will be excluded,and in the trehalase deficit, young mushrooms will be excluded.

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