Disaccharide Intolerance Type II

At a glance

It is a congenital enzyme defect resulting in chronic diarrhea, dehydration, and failure to thrive.

Synonyms

Congenital Lactase Deficiency; Disaccharidase Deficiency Type II.

Nature

Genetic disorder manifested by chronic diarrhea.

Incidence

Fewer than 100 cases have been reported worldwide, with the majority in Finland.

Genetic inheritance

It is inherited as autosomal recessive trait. The congenital lactase deficiency gene is localized on the long arm of chromosome 2.

Pathophysiology

Lactose, the main carbohydrate in milk and dairy products, is a disaccharide composed of glucose and galactose. In congenital lactase deficiency, the enzyme is present only at trace levels in the small intestine brush-border membrane. As a consequence of lactase deficiency, high concentrations of unabsorbed lactose remain in the intestinal lumen and generate an osmotic diarrhea.

Diagnosis

Clinical presentation, a trial of lactose-free diet, breath hydrogen test, and assay of lactase activity in a jejunal biopsy specimen.

Clinical aspects

Onset is very early in life (in the first hours or days of life), with watery diarrhea upon introduction of lactose-containing milks. Diarrhea is severe and results in rapid dehydration, malnutrition, failure to thrive, and high lactose concentration in the feces. Total remission with normal growth and psychomotor development occurs with a lactose-free diet.

Precautions before anesthesia

Evaluate volume status clinically and check serum electrolytes, blood urea nitrogen, and creatinine. Pay special attention to renal function and serum calcium levels because hypercalcemia and nephrocalcinosis have been described. Delay elective surgery until the patient hydration status is confirmed (good urine output with a chloride level >100) and acid-base status is corrected. If the patient is on total parenteral nutrition (TPN), also obtain serum concentrations of albumin, glucose, phosphate, magnesium, transaminases, alkaline phosphatase, and bilirubin. Optimize volume status preoperatively by intravenous rehydration.

Anesthetic considerations

Consider repeated intraoperative blood glucose monitoring if the patient is on TPN.

Pharmacological implications

In the presence of severe malnutrition (rare) or depressed renal and/or hepatic function secondary to complications from TPN, highly protein-bound drugs have to be titrated carefully, secondary to low protein levels (particularly α₁-acid glycoprotein and albumin), which may result in decreased drug binding and increased free drug levels.

Other conditions to be considered

• ☞Disaccharide Intolerance Type I: Congenital enzyme defect resulting in chronic diarrhea and failure to thrive.

• Severe Infantile Lactose Intolerance: On a lactate-containing diet, affected children become severely ill and present with vomiting, acidosis, lactosuria, aminoaciduria, and failure to thrive. Cataract occurs occasionally. ...