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home - Small Bowel - Miscellaneous - Lactose Intolerance Written by Dr Sebastian Zeki
Knowledge


Defines the pathophysiology of fluid and nutrient malabsorption,
including causes, e.g. anatomical and functional short bowel
syndrome, high output stomas, enterocutaneous fistulae and
pancreatic insufficiency

Knows how to investigate patients with malabsorption
Describes the clinical consequences of malabsorption, including
malnutrition, fluid and electrolyte disturbance and micronutrient
deficiency and anaemia and how to manage these

Describes all other causes of anaemia, including bone marrow
disorders and haemolysis

Describes the metabolism, absorption and bioavailability of iron, B12
and folate and clinical conditions and diets associated with their
deficiency

Skills
Identifies and appropriately investigates clinical features suggestive of
malabsorption

Manages fluid, electrolyte and micronutrient disturbances associated
with short bowel syndrome or high output stomas

Uses the appropriate investigations for the different types of anaemia
Behaviours
Takes a careful clinical approach to managing patients with
malabsorption and anaemia. Explains plan of management clearly to
patients and their relatives.

Lactose Intolerance

GlucoseandGalactase Lactose Intestinal Lactase Sodium dependent Glucose Carrier 75% lactose not absorbed in small bowel Developmental lactase deficiencyDue to prematurity- Lactase increases after 32 week gestationCongenital lactase deficiencyA rare autosomal recessive disorder.Most common in FinlandPathology: No small bowel lactase with normal levels of other disaccharidases.Clin Pres: Diarrhea from birth, hypercalcemia and nephrocalcinosis.Fatal prior to the development of lactose-free infant formulas.Age and ethnic lactose malabsorptionIn some ethnic groups lactase levels decrease from age 5In children lactose = 40% of daily calories ingested which falls to 5% in adultsLactase persistence in northern european countries (autosomal dom inheritance)Lactose Intolerance By Ethnicity:15% in Caucasian adults (being lowest in those of northern European extraction)90% among Native Americans and eatern Asia70% among Africans and African Americans.50 % in Hispanics Secondary lactose malabsorptionThis occurs with any small bowel problem.Lactase goes first as it is in a distal villus tip position.Treatment of the primary disorder can lead to restoration of lactase activity, which lags behind the return of normal intestinal morphology.Intolerance can persist for months after healing. Clinical Manifestations:Abdominal pain (lower quadrant/periumbilical).Bloating.Flatulence.Diarrhoea (bulky,frothy, watery).Particularly in adolescents, vomiting. Lactose tolerance testTest: 50g lactose load- blood glucose levels are monitored at 0, 60, and 120 minsPositive result: An increase in blood glucose by < 20 mg/dL (1.1 mmol/L) plus symptomsFalse negatives: Diabetes/ bacterial overgrowth/ rapid gastric emptyingSensitivity of 75 % and a specificity of 96 %. Lactose breath hydrogen testMeasures lactose nonabsorption.Give lactose- 2 g/kg. Breath hydrogen measured every 30 mins for 3 hoursResult: Breath hydrogen value of 10 ppm (parts per million) as normal.>20 ppm is diagnosticFalse-positives: recent smoking or not fastedFalse-negatives: Antibiotics, lung disorders, or in the 1% of subjects who are nonhydrogen producers.Small bowel biopsyIf lactose maldigestion discovered, then need to investigate for small bowel pathologyNormal breath hydrogen testsSymptoms may be due to psychologic factors and intolerance to other factors in milk.Consider maldigestion of other simple carbohydrates (eg, fructose, sorbitol) or of complex carbohydrates.Genetic test for primary lactose malabsorptionTest for the polymorphism C/C-13910 has been developedSensitivity and specificity were 93 and 100 %May not be suitable for African origin Treatment Lactose SCFA’s (butyrate, acetate, propionate) Anaerobic bacterial metabolism Hydrogen (used as basis for hydrogen breath test Milk Ice cream Cheese Reduce dietary lactose intake and substitute alternative energy sourcesLactose levels in milk and ice-cream > cheese Lactase supplements- Bacterial or yeast beta-galactosidases.-Variable results as only partially hydrolyze lactose-Lactaid liquid added to milk can pre-hydrolyse lactose-Lactrase capsules can be sprinkled on food-"Acidophilus milk" is not sufficiently lactose-depleted to be useful.Live culture yogurt, which contains endogenous beta-galactosidase, is an alternative source of calories and calcium, and is well-tolerated by many lactose-intolerant patients.Lactase-containing probiotics is of unproven benefitCalcium intakeNeed to monitor calcium and vitmain D levels Lactose Intolerance Primary lactose malabsorption Diagnosis Written by Dr Sebastian Zeki