Timely identification of lactose intolerance is crucial to prevent secondary complications. This study aimed to assess the diagnostic accuracy of three commonly used methods for detecting lactose malabsorption (LM): the lactose hydrogen breath test (LHBT), the lactose tolerance test (LTT), and the genetic test (GT).
Methods
Patients diagnosed with irritable bowel syndrome underwent fasting and post-lactose (20 g) evaluations, including measurements of breath hydrogen, blood glucose, and genotyping for the C/T-13910 polymorphism associated with lactase persistence in European populations. A sustained increase of breath hydrogen ≥20 ppm above baseline, a failure of plasma glucose to rise >20 mg/dL from fasting levels, and the presence of the C/T-13910 variant were defined as positive for LHBT, LTT, and GT, respectively.
Results
One hundred and eight patients (age 39 ± 14 years, 17 males) were enrolled. Eighty-eight had symptoms after lactose ingestion. Of these, 88 (100%) were LHBT and 69 (78%) were LTT positive. Of a subgroup of 33 patients undergoing GT, 27 presented symptoms and 25 tested positive. Sensitivity and specificity were 100% and 85% for LHBT, 78% and 48% for LTT, and 93% and 83% for GT.
Conclusions: With observation times greater than 4 h, LHBT had higher sensitivity and specificity than LTT and GT.
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