II. Indications
- Lactose Intolerance testing
III. Efficacy
- Preferred over Lactose Tolerance Test
- Test Sensitivity: 90%
IV. Technique
- Measure baseline breath hydrogen concentration
- Patient ingests lactose
- Classic: 25 to 50 grams lactose
- Physiologic: 12 grams lactose (same as in 8 oz milk)
- Measure breath hydrogen concentration in 3 to 8 hours
- Increase >20 ppm suggests Lactose Intolerance
V. False Negative causes
- Gastrointestinal flora absent (e.g. recent Antibiotics)
VI. False Positive causes
- Recent Exercise
- Aspirin use
- Tobacco Smoking
VII. References
- Powell in Goldman (2000) Cecil Medicine, p. 711