II. Indications

III. Efficacy

IV. Technique

  1. Measure baseline breath hydrogen concentration
  2. Patient ingests lactose
    1. Classic: 25 to 50 grams lactose
    2. Physiologic: 12 grams lactose (same as in 8 oz milk)
  3. Measure breath hydrogen concentration in 3 to 8 hours
    1. Increase >20 ppm suggests Lactose Intolerance

V. False negative causes

  1. Gastrointestinal flora absent (e.g. recent antibiotics)

VI. False positive causes

  1. Recent Exercise
  2. Aspirin use
  3. Tobacco smoking

VII. References

  1. Powell in Goldman (2000) Cecil Medicine, p. 711

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