Lactase Deficiency

  • Insufficient lactase enzyme → dietary lactose intolerance. Lactase functions on the intestinal brush border to digest lactose (in milk and milk products) into glucose and galactose.
    • Primary: age-dependent decline after childhood (absence of lactase-persistent allele), common in people of Asian, African, or Native American descent.
    • Secondary: loss of intestinal brush border due to gastroenteritis (eg, rotavirus), autoimmune disease, etc.
    • Congenital lactase deficiency: rare, due to defective gene.
  • Presentation: Bloating, cramps, flatulence, osmotic diarrhea.
  • Workup:
    • Stool demonstrates ↓ pH and breath shows ↑ hydrogen content with lactose hydrogen breath test.
    • Intestinal biopsy reveals normal mucosa in patients with hereditary lactose intolerance.
  • Treatment: Avoid dairy products or add lactase pills to diet; lactose-free milk.

Filipino MD

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