What are the diagnostic tests and treatment options for lactose intolerance?

Diagnostic Tests and Treatment for Lactose Intolerance

The most effective approach for diagnosing lactose intolerance is a 2-week dietary elimination trial followed by reintroduction, while management primarily involves gradual reintroduction of small amounts of dairy (up to 12 oz milk daily), lactose-free alternatives, and lactase supplements. 1

Diagnostic Tests

Initial Assessment

• Symptom Documentation: Record relationship between dairy consumption and symptoms (bloating, abdominal pain, flatulence, diarrhea) 1
• Food Diary: Track all food intake with specific attention to dairy products, noting timing and severity of symptoms 1
• Basic Laboratory Tests:
  • Complete blood count, CRP, ESR, albumin, electrolytes
  • Liver function tests, vitamin B12, folate, ferritin, calcium 1
  • Consider celiac disease testing (TTG antibodies) and fecal calprotectin 1

Diagnostic Methods

1. Elimination Trial (First-line approach):

   • Remove all dairy products for 2 weeks
   • Reintroduce dairy and observe for symptom recurrence 1
   • Simple, cost-effective, and clinically practical

2. Hydrogen Breath Test (Most widely used test):

   • Protocol: Overnight fast, ingestion of 25-50g lactose, breath samples at 15-30 minute intervals for 3 hours
   • Positive result: Rise in hydrogen >20 parts per million
   • Limitations: 25% false negative rate 1

3. Genetic Testing:

   • Testing for lactase-persistent alleles (LCT-13,910 C/T)
   • High sensitivity (89%) and specificity (94%) in certain populations 1

4. Stool Tests:

   • Presence of reducing substances (>0.5%) in stool
   • Note: Not diagnostic alone without clinical symptoms 2

Treatment Options

Dietary Management

• Gradual Reintroduction: Most people can tolerate 12-15g of lactose (approximately 1 cup of milk) 3
• Lactose-Free Alternatives: Maintain adequate nutrition while avoiding symptoms 1
• Strategic Consumption:
  • Consume dairy with other foods to slow digestion
  • Choose aged cheeses and yogurt (lower lactose content)
  • Distribute lactose intake throughout the day 1

Supplements and Medications

• Lactase Enzyme Supplements: Take before consuming dairy products 1
• Probiotics:
  • Specific strains like Lactobacillus acidophilus and Bifidobacterium can improve lactose digestion
  • Non-dairy probiotic options for severe intolerance 1
  • Mechanism: Provide microbial β-galactosidase, delay GI transit time, reduce symptom sensitivity

Special Considerations

• Address Underlying Conditions:
  • Treat primary conditions like celiac disease or SIBO
  • Allow intestinal mucosa to heal after infection or medication-induced damage 1
• Low FODMAP Diet: Consider for patients with overlapping IBS and lactose intolerance (under dietitian supervision) 1

Common Pitfalls to Avoid

• Misdiagnosis: Confusing lactose intolerance with milk protein allergy 1
• Overreliance on Tests: Proceeding directly to expensive testing without elimination trial 1
• Unnecessary Restrictions: Complete dairy avoidance is rarely needed; most can tolerate small amounts 3
• Ignoring Secondary Causes: Failing to consider intestinal damage from infections or celiac disease 1
• IgG Testing: Food elimination diets based on IgG antibodies are not recommended 1

Ethnic Considerations

• Prevalence varies significantly: 10% in Northern Europeans, 60% in Asians, and 90% in Chinese 1
• Genetic testing may be more reliable in populations with high prevalence of lactase-persistent alleles 1

Remember that lactose intolerance is a physiological condition due to lactase deficiency, not an immune-mediated reaction like milk protein allergy. With proper diagnosis and management, most patients can maintain adequate nutrition while minimizing symptoms.